Insert Imaging Device for Surgical Procedures

ABSTRACT

Insertable imaging devices, and methods of use thereof in minimally invasive medical procedures, are described. In some embodiments, insertable imaging devices are described that can be introduced and removed from an access port without disturbing or risking damage to internal tissue. In some embodiments, imaging devices are integrated into an access port, thereby allowing imaging of internal tissues within the vicinity of the access port, while, for example, enabling manipulation of surgical tools in the surgical field of interest. In other embodiments, imaging devices are integrated into an imaging sleeve that is insertable into an access port. Several example embodiments described herein provide imaging devices for performing imaging within an access port, where the imaging may be based one or more imaging modalities that may include, but are not limited to, magnetic resonance imaging, ultrasound, optical imaging such as hyperspectral imaging and optical coherence tomography, and electrical conductive measurements.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to U.S. Provisional Application No.61/801,746, titled “INSERT IMAGING DEVICE” and filed on Mar. 15, 2013,the entire contents of which is incorporated herein by reference. Thisapplication also claims priority to U.S. Provisional Application No.61/818,255, titled “INSERT IMAGING DEVICE” and filed on May 1, 2013, theentire contents of which is incorporated herein by reference. Thisapplication also claims priority to U.S. Provisional Application No.61/801,143, titled “INSERTABLE MAGNETIC RESONANCE IMAGING COIL PROBE FORMINIMALLY INVASIVE CORRIDOR-BASED PROCEDURES” and filed on Mar. 15,2013, the entire contents of which is incorporated herein by reference.This application also claims priority to U.S. Provisional ApplicationNo. 61/818,325, titled “INSERTABLE MAGNETIC RESONANCE IMAGING COIL PROBEFOR MINIMALLY INVASIVE CORRIDOR-BASED PROCEDURES” and filed on May 1,2013, the entire contents of which is incorporated herein by reference.This application also claims priority to U.S. Provisional ApplicationNo. 61/800,787, titled “POLARIZED LIGHT IMAGING DEVICE” and filed onMar. 15, 2013, the entire contents of which is incorporated herein byreference. This application also claims priority to U.S. ProvisionalApplication No. 61/800,911, titled “HYPERSPECTRAL IMAGING DEVICE” andfiled on Mar. 15, 2013, the entire contents of which is incorporatedherein by reference. This application also claims priority to U.S.Provisional Application No. 61/800,155, titled “PLANNING, NAVIGATION ANDSIMULATION SYSTEMS AND METHODS FOR MINIMALLY INVASIVE THERAPY” and filedon Mar. 15, 2013, the entire contents of which is incorporated herein byreference. This application also claims priority to U.S. ProvisionalApplication No. 61/924,993, titled “PLANNING, NAVIGATION AND SIMULATIONSYSTEMS AND METHODS FOR MINIMALLY INVASIVE THERAPY” and filed Jan. 8,2014, the entire contents of which is incorporated herein by reference.

BACKGROUND

The present disclosure is generally related to image guided medicalprocedures.

In the field of surgery, imaging and imaging guidance is becoming a moresignificant component of clinical care, from diagnosis of disease,monitoring of the disease, planning of the surgical approach, guidanceduring the procedure and follow-up after the procedure is complete, oras part of a multi-faceted treatment approach.

Integration of imaging data in the surgical suite has becomecommon-place for neurosurgery, where typically brain tumors are excisedthrough an open craniotomy approach guided by imaging. The data that isused typically consists of CT scans with or without associated contrast(iodinated contrast), and MRI scans with or without associated contrast(gadolinium contrast). Systems provide a means to register the imagingdata sets together, and registration methods to translate the threedimensional imaging space to the three dimensional space of the patientand tracking of instruments relative to the patient and the associateimaging data by way of an external hardware system such as a mechanicalarm, or an RF or optical tracking device.

SUMMARY

Insertable imaging devices, and methods of use thereof in minimallyinvasive medical procedures, are described. In some embodiments,insertable imaging devices are described that can be introduced andremoved from an access port without disturbing or risking damage tointernal tissue. In some embodiments, imaging devices are integratedinto an access port, thereby allowing imaging of internal tissues withinthe vicinity of the access port, while, for example, enablingmanipulation of surgical tools in the surgical field of interest. Inother embodiments, imaging devices are integrated into an imaging sleevethat is insertable into an access port. Several example embodimentsdescribed herein provide imaging devices for performing imaging withinan access port, where the imaging may be based one or more imagingmodalities that may include, but are not limited to, magnetic resonanceimaging, ultrasound, optical imaging such as hyperspectral imaging andoptical coherence tomography, and electrical conductive measurements.

Accordingly, in one aspect, there is provided a magnetic resonanceimaging probe comprising:

-   -   a longitudinal body;    -   first and second magnetic resonance coils supported by said        longitudinal body;    -   wherein said first coil is configured to measure fields having a        first direction within a region of interest beyond a distal        portion of said longitudinal body;    -   wherein said second coil is configured to measure fields having        a second direction within a region of interest beyond a distal        portion of said longitudinal body, wherein said first direction        and said second direction are approximately orthogonal;

and

-   -   electrical circuits housed within said longitudinal body for        tuning and matching said first and second coils and        preamplifying signals detected by said first and second coils.

In another aspect, there is provided a magnetic resonance imaging probecomprising:

-   -   a longitudinal body;    -   one or more magnetic resonance coil arrays supported by said        longitudinal body, wherein at least one coil array is a planar        stripline array comprising:        -   an array of parallel stripline conductors provided near a            distal portion of said longitudinal body, wherein said array            of parallel stripline conductors lies in a plane that is            approximately orthogonal to a longitudinal axis of said            longitudinal body;        -   each stripline conductor having longitudinal conductive            paths extending from ends thereof and contacting a coil loop            at a location that is remote from said distal portion; and        -   a tuning capacitor serially provided within each            longitudinal conductive path; and    -   a plurality of matching and preamplification circuits housed        within said longitudinal body, wherein each matching and        preamplification circuits is operatively coupled to a single        stripline conductor.

In another aspect, there is provided a magnetic resonance imaging probecomprising:

-   -   a longitudinal body;    -   one or more magnetic resonance coil arrays supported by said        longitudinal body, wherein at least one coil array is an axial        stripline array comprising:        -   an array of parallel stripline conductors cylindrically            arranged and extending in a longitudinal direction;        -   each stripline conductor having radial conductive paths            extending from ends thereof and contacting an inner ground            conductor; and        -   a tuning capacitor serially provided within each            longitudinal conductive path; and    -   a plurality of matching and preamplification circuits housed        within said longitudinal body, wherein each matching and        preamplification circuits is operatively coupled to a single        stripline conductor.

In another aspect, there is provided a magnetic resonance imaging probecomprising:

-   -   a longitudinal body portion comprising one or more magnetic        resonance imaging coils;    -   a handle portion that is removably connectable to said        longitudinal body portion, wherein an electrical connection is        formed between said longitudinal body portion and said handle        portion upon mechanical connection of said longitudinal body        portion to said handle portion;    -   at least one electrical circuit for tuning and matching said        coils and preamplifying signals detected by said coils, wherein        said electrical circuit is divided among said longitudinal body        portion and said handle portion, and wherein at least a        preamplification portion of said electrical circuit is housed        within said handle portion.

In another aspect, there is provided a magnetic resonance imaging probecomprising:

a longitudinal body;

one or more magnetic resonance coils housed within said longitudinalbody, wherein at least one coil is a folded stripline coil comprising:

-   -   two longitudinal stripline conductors having a ground plane        conductor provided therebetween;    -   a folded conductor segment connecting said two longitudinal        stripline conductors near a distal portion of said longitudinal        body;    -   a pair of matching capacitors, each matching capacitor provided        between one of said longitudinal stripline conductors and said        ground plane conductor;    -   a tuning capacitor serially provided within one of said        longitudinal stripline conductors; and

a preamplifier circuit housed within said longitudinal body, whereinsaid preamplifier circuit is operatively coupled to said foldedstripline coil.

In another aspect, there is provided a magnetic resonance imaging probefor performing intraoperative imaging during a minimally invasivemedical procedure involving an access port, the probe comprising:

-   -   a probe body comprising a cylindrical body portion configured to        be slidably and removably received within an inner lumen of the        access port, said cylindrical body portion comprising one or        more magnetic resonance imaging coils;    -   at least one electrical circuit housed within said probe body        for tuning and matching said coils and preamplifying signals        detected by said coils; and    -   one or more air passage features provided on or with said        cylindrical body portion for facilitating expulsion of air from        the inner lumen of the access port during insertion of said        cylindrical body portion into the access port.

In another aspect, there is provided an access port for performingintraoperative imaging during a minimally invasive medical procedurewhile providing access to internal tissue, the access port comprising:

-   -   a hollow cylindrical body configured to be inserted into a        subject for providing access to internal tissue;    -   one or more imaging elements integrated with and supported by        said hollow cylindrical body;    -   one or more externally accessible connectors positioned near a        proximal region of said hollow cylindrical body; and    -   at least one connection channel integrated with said hollow        cylindrical body for supporting signal transmission between said        externally accessible connectors and said imaging elements;    -   wherein at least one of said imaging elements is configured for        imaging a distal region of interest beyond a distal end of said        hollow cylindrical body.

In another aspect, there is provided an imaging sleeve for performingintraoperative imaging during a minimally invasive medical procedureinvolving an access port, the imaging sleeve comprising:

-   -   a hollow cylindrical body configured to be slidably and        removably received within an inner lumen of the access port;    -   one or more imaging elements integrated with and supported by        said hollow cylindrical body, wherein said imaging elements are        positioned for imaging through the access port;    -   one or more externally accessible connectors positioned near a        proximal region of said hollow cylindrical body; and    -   at least one connection channel integrated with said hollow        cylindrical body for supporting signal transmission between said        externally accessible connectors and said imaging elements.

In another aspect, there is provided an

A further understanding of the functional and advantageous aspects ofthe disclosure can be realized by reference to the following detaileddescription and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments will now be described, by way of example only, withreference to the drawings, in which:

FIG. 1 illustrates the insertion of an access port into a human brain,for providing access to internal brain tissue during a medicalprocedure.

FIGS. 2A and 2B illustrate an example implementation of an insertableimaging probe that is insertable into an access port, showing the device(A) prior to insertion and (B) after insertion.

FIG. 3 illustrates an example implementation of an insertable imagingprobe that includes external features that allow the passage of gasduring insertion or withdrawal of the insertable imaging probe.

FIG. 4 illustrates an example implementation of an insertable imagingprobe and an access port that have corresponding features for aligningthe insertable imaging probe during its insertion into the access port.

FIGS. 5A and 5B show an insertable imaging probe having a disposableouter sheath.

FIGS. 6A-6B illustrate an example insertable imaging probe in which adisposable body portion is connected to a handle portion by a connectionmechanism.

FIGS. 7A and 7B illustrate an example implementation of an insertableimaging probe that has an atraumatic distal tip, such that theinsertable imaging probe may function as an imaging introducer orimaging obturator capable of performing imaging during inserting of theaccess port.

FIG. 8 is an illustration demonstrating an example simplifiedneurosurgical configuration.

FIG. 9 illustrates an example implementation of an imaging sleeve thatincludes a single or multiple imaging elements.

FIG. 10 shows one example embodiment of a combination of severalinsertable imaging devices, involving a non-imaging access port and twocoaxial imaging sleeves inserted into the access port.

FIG. 11 shows another example embodiment of a combination of severalinsertable imaging devices, involving a non-imaging access port, animaging sleeve inserted into the access port, and an insertable imagingprobe.

FIG. 12 shows another example embodiment of a combination of severalinsertable imaging devices, involving an access port with integratedimaging element(s) and an insertable imaging probe.

FIG. 13 shows another example embodiment of a combination of severalinsertable imaging devices, involving an access port with integratedimaging element(s), an imaging sleeve inserted into the access port, andan insertable imaging probe.

FIG. 14 schematically illustrates an example magnetic resonance imagingsystem that includes an insertable magnetic resonance imaging device.

FIG. 15 schematically illustrates an example implementation of circuitfor receiving signals from a magnetic resonance coil element within aninsertable MR imaging device.

FIGS. 16A-C illustrate an example coil configuration employing a foldedstripline resonator.

FIGS. 17A-B illustrate an example coil configuration employing a foldedstripline resonator in which the electronics are provided within thehandle portion, while the coil element is provided in a disposable orsterilizable body portion.

FIG. 18 illustrates an example coil configuration employing a two foldedstripline resonators arranged in a quadrature configuration.

FIGS. 19A-C illustrate example embodiments where stripline resonatorsare provided at or near the distal portion of the MR imaging probe,either in a linear (A, B) or (C) radial configuration.

FIGS. 20A-D illustrate various example implementations of a loop coilconfiguration.

FIGS. 21A-B illustrate example coil loop implementations involving (A)two and (B) four folded loop coils that are provided at or near thedistal portion of the MR imaging probe.

FIGS. 22A-C illustrate three example coil implementations involvingbutterfly coil configurations.

FIG. 23 illustrates an example implementation of an embodiment in whichmultiple coil types are combined within an MR imaging probe to produce aprobe that is sensitive to magnetization beyond the distal region of theimaging probe.

FIG. 24 illustrates an example implementation of an embodiment in whichmultiple coil types are combined within an MR imaging probe.

FIG. 25 illustrates an example implementation of an insertable MRimaging probe having a dense array of coils.

FIG. 26 is an illustration demonstrating the imaging coverage on a brainusing multiple coil arrays.

FIG. 27 illustrates an example implementation of an insertable MRimaging probe having an array of loop coils arranged near a distalsurface of the insertable MR imaging probe, in a configuration forend-fire array-based imaging.

FIGS. 28A-B illustrate an example implementation of an imaging probearranged to be in quadrature with butterfly arrays.

FIG. 29 illustrates an example implementation of an imaging probealigned parallel to enable high parallel imaging factors in a singledirection.

FIG. 30 illustrate an example implementation of an imaging probe havingstrip line coil overlaid with a loop coil.

FIGS. 31A-B illustrates an alternate embodiment where each striplinecoil is overlaid with a loop coil to form an array.

FIG. 32 shows in example implementation of an insertable MR imagingprobe having a swivelling tip.

FIG. 33 illustrates an example implementation in which the probe tipincludes a wrist rotatable in varying angles.

FIG. 34 illustrates an example implementation of an insertable MRimaging probe in which variable bending of the probe tip is achievedthrough the use of oppositely placed cables located along the wall ofthe bendable portion.

FIG. 35 illustrates an example insertable MR imaging probe having aforward-looking (e.g. end-fire) configuration, where the distal regionof the probe body includes one or more expandable coil elements.

FIGS. 36A-36D illustrates an example of embedding coils in the sidewalls of a port.

FIG. 37 illustrates an embodiment of a probe showing the correctpositioning relative to the B₀ field.

FIGS. 38A-D illustrate various example implementations of access portswith integrated MR coil arrays.

FIG. 39 illustrates an example implementation of a multi-deviceinsertable imaging probe.

FIG. 40 illustrates an alternative coil configuration employed inanother experimental implementation of an insertable MR imaging device,in which stripline and loop geometries were included.

FIG. 41 shows an image of a sheep's brain acquired with an MR imagingprobe having the coil configuration shown in FIG. 40.

FIG. 42 shows an image of the same sheep brain acquired with the sameresolution using a 32 channel head coil at 3.

FIG. 43 shows an image acquired with the example MR imaging probe basedon the coil design shown in FIG. 40.

FIG. 44 shows the identical object imaged with a 32 channel head coil.

FIG. 45 is a flow chart illustrating an example method of selectivelyaddressing selected coils within a coil array in order to achieve asmart coil array.

FIG. 46 illustrates an example insertable MR imaging probe containing anarray of MR coils, where only a subset of coils are employed forscanning, based on comparing the coil signals to pre-selected criteria.

FIG. 47A illustrates an example implementation of an insertable MRimaging probe containing a cylindrical magnet that generates the B₀field.

FIG. 47B illustrates the use of local gradient coils for producing agradient field for an insertable MR imaging probe having an internalB₀-generating magnet.

FIGS. 48A-C illustrate an example coil configuration for an insertableMR imaging probe having an internal B₀-generating magnet, where coilelements are arranged such that their imaging area can be used todetermine spatial encoding in the θ and z directions.

FIG. 49 illustrates an example implementation of an insertable MRimaging probe containing a spherical magnet that generates the B₀ field.

FIGS. 50A-C illustrate three example implementations of an insertableultrasonic imaging probe having one or more distal ultrasonictransducers for imaging tissues in a forward-looking direction within anaccess port.

FIG. 51 illustrates an example implementation of an insertableultrasonic imaging probe having an ultrasonic transducer integratedtherein.

FIGS. 52A-F illustrate example implementations of an insertableultrasonic imaging introducer having of a single radial array ofultrasound transducers positioned such that optical view through theintroducer tip is not occluded.

FIGS. 53A-C illustrate another example implementation of an insertableultrasonic imaging probe having an ultrasonic transducer integratedtherein, where the introducer includes an opening.

FIGS. 54A-C illustrate another example implementation of an insertableultrasonic imaging probe having an ultrasonic transducer integratedtherein, where the introducer includes an opening and a non-conical tip.

FIG. 55 illustrates an example implementation of an access port havingan array of conductive elements on an outer surface thereof forperforming a measurement of a resistance map.

FIG. 56 illustrates an example implementation of an introducer having anarray of sensing elements for making physiological measurements.

FIG. 57 illustrates an example implementation of an access port havingan array of sensing elements for making physiological measurements.

FIG. 58 illustrates light guides in walls of access port.

FIG. 59 illustrates light guides in insertable sleeve.

FIG. 60 illustrates light guides in insert device.

FIG. 61 illustrates different configuration for distal end of lightguide.

FIG. 62 illustrates an example implementation an access port orintroducer having a conical distal portion that preserves the visibilityof the path ahead of the conical portion.

FIGS. 63A-D illustrate embodiments of an access port in which the wallsof the access port are configured to guide light to a distal portion ofthe port via total internal reflection.

FIG. 64 is an exemplary embodiment of an ultrasound imaging assembly.

FIG. 65 shows a flowchart depicting the stages of minimally invasiveport based surgical procedure where imaging is valuable as an integraltool.

FIG. 66 is an illustration demonstrating an example embodiment involvinginsert imaging devices with differing imaging fields and resolutions.

FIG. 67 is an illustration demonstrating an example embodiment involvingthe use of microarrays attached to a port.

FIG. 68 shows a flowchart depicting the utilization of imaging data forcraniotomy/incision guidance.

FIG. 69 shows a flowchart depicting the utilization of imaging data forguidance of the access port.

FIG. 70 shows a flowchart depicting the utilization of imaging data forde-bulking of diseased tissue.

FIG. 71 shows a flowchart depicting the utilization of imaging data forsurgical closure verification.

FIG. 72 shows a flowchart depicting the utilization of imaging data forprecision zone resection.

FIG. 73 shows a flowchart depicting the utilization of imaging data fortissue margin treatment.

FIG. 74 is an illustration demonstrating an example port with a surfacein-situ imaging array.

DETAILED DESCRIPTION

Various embodiments and aspects of the disclosure will be described withreference to details discussed below. The following description anddrawings are illustrative of the disclosure and are not to be construedas limiting the disclosure. Numerous specific details are described toprovide a thorough understanding of various embodiments of the presentdisclosure. However, in certain instances, well-known or conventionaldetails are not described in order to provide a concise discussion ofembodiments of the present disclosure.

As used herein, the terms, “comprises” and “comprising” are to beconstrued as being inclusive and open ended, and not exclusive.Specifically, when used in the specification and claims, the terms,“comprises” and “comprising” and variations thereof mean the specifiedfeatures, steps or components are included. These terms are not to beinterpreted to exclude the presence of other features, steps orcomponents.

As used herein, the term “exemplary” means “serving as an example,instance, or illustration,” and should not be construed as preferred oradvantageous over other configurations disclosed herein.

As used herein, the terms “about” and “approximately” are meant to covervariations that may exist in the upper and lower limits of the ranges ofvalues, such as variations in properties, parameters, and dimensions. Inone non-limiting example, the terms “about” and “approximately” meanplus or minus 10 percent or less.

Unless defined otherwise, all technical and scientific terms used hereinare intended to have the same meaning as commonly understood to one ofordinary skill in the art. Unless otherwise indicated, such as throughcontext, as used herein, the following terms are intended to have thefollowing meanings:

As used herein, the phrase “access port” refers to a cannula, conduit,sheath, port, tube, or other structure that is insertable into asubject, in order to provide access to internal tissue, organs, or otherbiological substances. In some embodiments, an access port may directlyexpose internal tissue, for example, via an opening or aperture at adistal end thereof, and/or via an opening or aperture at an intermediatelocation along a length thereof. In other embodiments, an access portmay provide indirect access, via one or more surfaces that aretransparent, or partially transparent, to one or more forms of energy orradiation, such as, but not limited to, electromagnetic waves andacoustic waves.

As used herein the phrase “intraoperative” refers to an action, process,method, event or step that occurs or is carried out during at least aportion of a medical procedure. Intraoperative, as defined herein, isnot limited to surgical procedures, and may refer to other types ofmedical procedures, such as diagnostic and therapeutic procedures.

Embodiments of the present disclosure provide imaging devices that areinsertable into a subject or patient for imaging internal tissues, andmethods of use thereof. Some embodiments of the present disclosurerelate to minimally invasive medical procedures that are performed viaan access port, whereby surgery, diagnostic imaging, therapy, or othermedical procedures (e.g. minimally invasive medical procedures) areperformed based on access to internal tissue through the access port.

An example of an access port is an intracranial access port which may beemployed in neurological procedures in order to provide access tointernal tissue pathologies, such as tumors. One example of anintracranial access port is the BrainPath surgical access port providedby NICO, which may be inserted into the brain via an obturator with anatraumatic tip in the brain. Such an access port may be employed duringa surgical procedure, by inserting the access port, via the obturatorthat is received within the access port, through the white matter fibersof the brain to access a surgical site.

For example, FIG. 1 shows an access port 12 inserted into a human brain10, providing access to internal brain tissue. Surgical tools andinstruments may then be inserted within the lumen of the access port inorder to perform surgical, diagnostic or therapeutic procedures, such asresecting tumors as necessary. This approach allows a surgeon, orrobotic surgical system, to perform a surgical procedure involving tumorresection in which the residual tumor remaining after is minimized,while also minimizing the trauma to the intact white and grey matter ofthe brain. In such procedures, trauma may occur, for example, due tocontact with the access port, stress to the brain matter, unintentionalimpact with surgical devices, and/or accidental resection of healthytissue.

As noted above, some embodiments of the present disclosure provideinsertable imaging devices that may be employed during suchaccess-port-based procedures. The use of imaging devices within anaccess port, or the incorporation of imaging devices into an accessport, provides additional interoperative images and data that mayimprove the accuracy, efficiency, and effectiveness of medicalprocedures. In some embodiments, methods and devices are described forperforming imaging with an insertable imaging device that can beintroduced and removed from an access port without disturbing or riskingdamage to internal tissue. In some embodiments, devices are integratedinto an access port, thereby allowing imaging of internal tissues withinthe vicinity of the access port, while, for example, enablingmanipulation of surgical tools in the surgical field of interest.Several example embodiments described herein provide imaging devices forperforming imaging within an access port, where the imaging may be basedone or more imaging modalities that may include, but are not limited to,magnetic resonance imaging, ultrasound, optical imaging such ashyperspectral imaging and optical coherence tomography, and electricalconductive measurements.

For example, in some embodiments, insertable imaging devices maysimultaneously accommodate multiple imaging modalities. Insertableimaging devices according to the present disclosure can be also beintegrated into currently available (e.g. conventional) imaging systems,such as MRI scanners, or may be interfaced with a dedicated imagingsystem. In other embodiments, insertable imaging devices may beconfigured to accommodate point measurement devices and modalities suchas, but not limited to, a Raman touch probe and conductance or pressuremeasurement (e.g. involving measurements made at a single point oracross an array of sensors).

It is to be understood that while many of the embodiments describedherein relate to access-port-based neurological procedures, theembodiments provided herein, unless otherwise stated, may be employedfor a wide range of medical procedures, involving a wide range ofanatomical regions of the body. For example, various embodiments may beemployed for imaging during procedures such as endorectal andendovaginal procedures. Furthermore, while many of the embodiments ofthe present disclosure relate to access-port-based procedures, someembodiments, such as insertable imaging probes described herein, may beemployed with or without an access port.

As describe below, an insertable imaging device may, in someembodiments, include at least one imaging array employing at least oneimaging modality. Examples of imaging modalities include magneticresonance MR imaging, ultrasound, optical imaging (such as, but notlimited to visible 2D-3D imaging, optical coherence tomography,hyper-spectral imaging, polarized light imaging, Raman Imaging, andfluorescence Imaging), electrophysiology, optical coherence tomography,X-ray (computerized tomography, spectral X-ray), photo-acoustic imaging,positron emission tomography, thermal imaging, electromechanical arrays(strain gauges, ionic conductors), and biosensor arrays. It will also beunderstood that these modalities may be used in receive and/ortransmission mode, and may be used in conjunction with an externaltransmission or receiving system, and image processing system. Someembodiments may include a means to transmit the signals to and from thedetectors/transmitters and coordinate the image acquisition, and imagealignment. Some embodiments may also include a means to integrate theacquired information with a previously acquired volumetric image data.

The present disclosure is organized as follows. Section 1 presentsvarious embodiments of insertable imaging device that are generic to awide range of imaging modalities, where the generic embodiments includeinsertable imaging probes, access ports with integrated imagingelements, and embodiments involving various combinations of insertableimaging probes and access ports with integrated imaging elements.Section 2 describes various embodiments of insertable imaging probes andaccess ports with integrated imaging elements that are configured formagnetic resonance imaging. Additional sections of the presentdisclosure describe additional imaging modalities, and embodimentsinvolving multimodal imaging.

1. Insertable Imaging Devices 1.1 Insertable Imaging Probe

In some embodiments, an insertable imaging probe is provided that isinsertable into an access port. FIGS. 2A and 2B illustrate an exampleimplementation of such an embodiment, in which an insertable imagingprobe is shown in FIG. 2A prior to insertion into an access port, andFIG. 2B after insertion into the bore of the access port. As shown inthe FIG. 2A, access port 12 includes a sheath portion 14 defining aninternal bore 16, and an external flange 18. Insert imaging probe 20includes longitudinal body portion 22 and may include a handle portion24. The insertable imaging probe 20 may be guided within the bore 16 ofaccess port 12 in order to provide intra-operative imaging of internaltissues accessible within access port 12, such as anterior tissuesbeyond the distal end of the access port 12, and lateral tissuessurrounding the lateral portions of access port 12. The body portion 22may be provided with a rounded end (for example, with a slightly roundedend as shown in the FIG. 2A and FIG. 2B) in order to facilitate smoothentry into the bore of an access port 12.

Body portion 22 of insert imaging probe 20 houses one or more imagingelements 26, such as an array of imaging elements. As noted above, theimaging elements may employ one or more imaging modality including, butnot limited to MRI, ultrasound, optical imaging (such as, but notlimited to visible 2D-3D imaging, optical coherence tomography,hyper-spectral imaging, polarized light imaging, Raman Imaging, andfluorescence Imaging), electrophysiology, X-ray (computerized tomography(CT), spectral X-ray), photo-acoustic imaging, positron emissiontomography (PET), thermal imaging, electromechanical arrays (straingauges, ionic conductors), and biosensor arrays.

It will be understood that the volume of internal tissue that may beimaged when the insertable imaging device is inserted into the accessport will depend on the specific imaging modality or modalities employedby the insertable imaging probe, as well as the specific configurationand orientation of the imaging elements.

The dimensions of the insertable imaging probe may be selected such thatthe probe may fit within a pre-selected access port. For example, theinsert imaging probe may have a diameter such that upon insertion of theinsertable imaging probe into the access port, the insert imaging portis received within the access port. Accordingly, the outer diameter ofthe body portion of the insert imaging probe may be selected to besufficiently large that the insert imaging probe makes contact with theinner wall of the access port during its introduction therein. Forexample, the outer diameter of the insertable imaging probe may beselected such that the insertable imaging probe frictionally engageswith the inner wall of the access port during insertion. For example,the outer diameter of the insert imaging probe may be selected to begreater than 95%, or greater than 98% or greater than 99%, of the innerdiameter of the access port.

Such embodiments, which provide for a close fit between the insertableimaging probe and the access port, may be beneficial in maintaining asuitable orientation of the insertable imaging probe during itsinsertion within the access port, and/or for supporting the insertableimaging probe in a prescribed orientation during its insertion into theaccess port.

In order to facilitate insertion of the insertable imaging probe intothe access port, the insertable imaging probe may include one or moreair passage features that facilitate the expulsion of air from the boreof the access port during insertion of the insertable imaging probe intothe access port, and to facilitate the introduction of air into the boreof the access port during withdrawal of the insertable imaging probe.

FIG. 3 illustrates one example implementation of an insertable imagingprobe 20 that has grooves 28 (e.g. channels or recesses) formed withinits outer surface that allow gasses to escape during insertion or beintroduced during withdrawal, thus preventing a vacuum effect fromoccurring. As shown in FIG. 3, the grooves 28 may be longitudinalgrooves. In other example implementations, the grooves may extend inalternative orientations, such as in a serpentine configuration or athreaded configuration, such that groove spans the longitudinal extentof the insertable imaging probe 20. In an alternative embodiment,insertable imaging probe 20 may include a longitudinal channel formedwith the body of the insertable imaging probe 20, as opposed to on thesurface of the insertable imaging probe 20. It will be understood thatthe grooves, channels, or passages need not be completely open, and mayinstead be filled with a gas-permeable material that can resist fluidflow while allowing the passage of a gas.

As described further below, the close fit between the insertable imagingprobe and the access port reduces the amount of air between the imagingprobe and the access port. This may be useful in improving image qualityfor selected imaging modalities. For example, the presence of air canlead to image distortion in magnetic resonance imaging due todifferences in susceptibility between air, tissue, and the materialsforming the access port and the insertable imaging probe. In anotherexample, in which the insertable imaging probe employs an acoustic oroptical imaging modality, the presence of an air gap may lead to lossesin signal and/or signal artifacts due to multiple reflections. In suchcases, the imaging probe may be coated with a material such as a liquidor gel in order to improve the matching of impedances between theinsertable imaging probe and the access port.

In alternate implementations, insertable imaging probes may havedifferent diameters suitable for several different types of accessports. For example, an insertable imaging probe may have a diametersuitable to be received within the NICO Brainpath access port, which iscurrently available in several lengths: 50 mm, 60 mm and 75 mm, wherethe inner diameter is 13.5 mm. Different lengths are used depending ofdepth of tumor/target. An imaging probe for use with such a port wouldhave a diameter less than 13.5 mm. An imaging probe that needs to bemoved directionally within the port would have a diameter significantlyless than 13.5 mm. In one example implementation, an imaging probe thatis intended to slide freely along the axis of the port could have adiameter between approximately 12 mm and 13.4 mm. In other exampleimplementations, an insertable imaging probe may have a diametersuitable for other types of access ports, such as access ports suitablefor abdominal or spinal surgical procedures.

In some embodiments, the insertable imaging probe and the access portmay include corresponding features (e.g. they may be mutually keyed)that require the access port to be oriented in a prescribed angularrelationship relative to the access port during the initial stages ofinsertion. This may be beneficial in improving and/or verifying theregistration of the insertable imaging probe relative to the accessport. An example implementation of such an embodiment is shown in FIG.4. In this embodiment, one of the outer surface of the insert imagingprobe 47 and the inner surface 48 of the access port may include aprotrusion 45, and the other may include a recess 46 configured toreceive the protrusion when the insertable imaging probe is inserted ina prescribed orientation.

1.1.1 The Probe Housing

As describe above, several embodiments of the present disclosure provideinsert imaging probes that comprise a cylindrical body portion that isconfigured for insertion into an access port having a cylindrical bore.In some applications, a portion of the insertable imaging probe may becontacted with tissue (or could potentially be contacted with tissue)during a medical procedure. For example, in some embodiments describedherein, the distal portion of the insertable imaging probe may contacttissue when the probe is inserted into an access port or conduit havinga distal opening (aperture). Accordingly, in some embodiments, at leastpart of the body portion of the insertable imaging probe may have anexternal surface formed from a material that is bio-compatible. Examplesof suitable biocompatible materials include polyurethane, polycarbonate,or Teflon.

In some embodiments, at least one portion of the insertable imagingprobe may be disposable and/or sterilizable. For example, the bodyportion of the insertable imaging probe may have an outer sheath orshell that is disposable, as shown in FIGS. 5A and 5B.

In some embodiments, the insertable imaging probe 20 may include adisposable and/or sterilizable (e.g. autoclavable) portion 34 that isconnectable, via a connection mechanism such as a locking mechanism, tothe handle portion. This handle, which may or may not be disposable, mayalso serve to store electrical components and/or to route cables back tothe processing system as a whole. Incorporating some or all of thecircuit elements within the handle of the probe enables the slimsilhouette of the port coil.

For example, FIGS. 6A and 6B illustrate an example embodiment in whichinsertable imaging probe 20 includes a body portion 22 that isattachable or connectable to a handle portion 24 via a connectionmechanism 40. The electrical and imaging components 26 contained withinthe insertable imaging probe 20 may be divided into two groups:components that are housed within the handle, and components that arehoused within the insertable and optionally disposable body portion ofthe insertable imaging probe. In some embodiments, at least some of theelectrical components of the insertable imaging probe are housed withinthe handle 24, while other components, such as other electricalcomponents and imaging elements or imaging assemblies, are housed withinthe disposable body portion.

For example, in the case of a magnetic resonance imaging probe, at leastsome of the electrical components, such as at least some components ofthe tuning and matching circuit, or preamplifier circuit, may be housedwithin the handle portion 24, while other components, such as one ormore electrical coils, may be housed within the body portion 22 of theinsertable imaging probe 20. The handle portion 24 may be mechanicallyand electrically connected to the body portion when the body portion isattached to (e.g. locked to) the handle 24. The mechanism 40 may beprovided at the interface of the two components to ensure unique andunambiguous mating of the two parts. In one non-limiting exampleimplementation, this connection mechanism may be provided by circularmating connectors with uniquely arranged grooves and corresponding pinsor keys 42 which ensure correct polarization of the contacts 44.

In some example embodiments, a handle may be provided that is removablyconnectable to different body portions, where each body portion has adifferent coil orientation. For example, one body portion may include anendonasal coil with two orthogonal striplines, while another body potionmay include a port coil using an orthogonal loop and a stripline. Aslong as the coil elements are tuned outside of the handle, thepreamplifier could be located in the handle.

1.1.2 Markings on Insertable Imaging Probe

In some embodiments, the insertable imaging probe may have delineatedmarkings to assist in the positioning of the insertable imaging probewithin the access port. For example, the body portion of the insertimaging probe may have graduated measurement markings to provide depthinformation when guiding the port into the access probe.

In other example implementations, the insertable imaging probe mayinclude one or more directional markings identifying an orientation ofthe probe relative to a preferred orientation. For example, inembodiments in which the insertable imaging device includes one or moremagnetic resonance imaging coils, the body or handle of the imagingprobe may include a directional marker identifying a preferredorientation of the insertable imaging probe relative to the B₀ magneticfield. Alternatively, in the example case of an insertable imaging probethat is configured for performing polarization sensitive imaging, theinsertable imaging probe may have one or more directional markersidentifying one or more polarization axes.

1.1.3 Single Element Insertable Imaging Probes

In some embodiments, an insertable imaging probe (or an imagingintroducer) may including a single imaging element, such as a single MRcoil or a single ultrasound transducer. In such cases, 2D and/or 3Dimaging may be realized by mechanically (robotically) rotating theinsertable imaging probe during insertion or removal of the insertcomponent, and subsequently reconstructing the volume image through theuse of software reconstruction methodologies based on a trackedorientation and position of the insertable imaging probe. In someembodiments, two or more imaging elements may be employed, where eachelement is associated with a different imaging modality. Suchembodiments are described in more detail below.

1.1.4 Insertable Imaging Probes with Multi-Element Imaging Arrays

In other embodiments, an insertable imaging probe (or an imagingintroducer) may including a plurality of imaging elements (e.g. an arrayof imaging elements), such as an array of MR coils, and an array ofultrasound transducers. Such embodiments are described in more detailbelow.

1.2 Imaging Introducer for Access Port

In some embodiments, the insertable imaging probe may have an atraumaticdistal tip, such that the insertable imaging probe may function as anintroducer or obturator for inserting the access port into the subjector patient in order enable the collection of images during theintroduction of the access port, while reducing trauma and collateraldamage to internal tissue. One example embodiment is illustrated inFIGS. 7A and 7B. FIG. 7A shows imaging probe 50 having body portion 52and atraumatic tip 54. As noted above, imaging probe 50 may also haveone or more channels formed in its external surface (or within its body)in order to provide a path for the passage of gases during insertion orwithdrawal. FIG. 7B shows imaging probe 50 received within access port12, where atraumatic tip 54 extends through a distal aperture withinaccess port 12. The angle of the atraumatic tip 54 may be chosen torender the tip atraumatic for a given tissue type, or set of tissuetypes. For example, in the case of intracranial neurological procedures,suitable angles include 15 to 30 degrees.

1.3 Access Port with Integrated Imaging Elements

In the preceding embodiments, insertable imaging devices were describedas insertable imaging probes that may be configured for use with anaccess port. However, in other embodiments, the access port itself mayhave imaging elements formed therein or thereon. For example, the accessport may have integrated imaging elements, such as, but not limited to,magnetic resonance MR imaging, ultrasound, optical imaging devices (suchas, but not limited to visible 2D-3D imaging), optical devices and/orconduits for performing optical coherence tomography, hyper-spectralimaging, polarized light imaging, Raman Imaging, and fluorescenceImaging), electrophysiology, photo-acoustic imaging, thermal imaging,electromechanical arrays (strain gauges, ionic conductors), andbiosensor arrays.

An external connection to the proximal end of the access port could bemade with connectors such as pins and sockets, with push-on connectors(such as MCX, or SMB), or threaded coaxial connectors such as SMA, orany other multi-pin connector. If the connector is to be used in amagnetic resonance imaging system, it connector should be non-magnetic.

1.4 Insertable Sleeves with Integrated Imaging Elements

In some embodiments, an insertable imaging device may be provided in theform of an imaging sleeve that is insertable into an access port. Forexample, FIG. 9 illustrates an example embodiment of an insertableimaging device 55 having an imaging sleeve 56 comprising a central bore58 and imaging element 57 provided thereon. In alternate embodiments,imaging element 57 may also be provided thereon. In FIG. 9, imagingsleeve 56 includes a single imaging element 57, where imaging element 57is positioned for lateral imaging, and where imaging element 57generally collects image data through the side wall of access port 20.The imaging element 57 is energized by control circuit placed in imagingprobe 50 (shown in FIG. 7B) through contact points 59. The contactpoints ensure good connectivity using a press-fit mechanism or othersimilar design features between the imaging sleeve 56 and the probe end55. For example, the imaging sleeve shown in FIG. 9 could be employedfor performing a surface or volumetric image by rotating the sleevewhile inserting or removing the sleeve, and collecting image datacorrelated with the position and orientation of the imaging sleeve.

In an alternative embodiment, in which an imaging element isincorporated into the sleeve near or at a distal region of the imagingsleeve, such that it is oriented for imaging a tissue region beyond thedistal end of the imaging sleeve (e.g. by imaging in a longitudinaldirection). In such an embodiment, the imaging element may obtain imagesthrough the bottom of the access port, or directly from the internaltissue, depending on the configuration of the distal end of the accessport (e.g. depending on whether or not an aperture is present in theaccess port, or depending on the width of an aperture in the accessport). The region imaged by the imaging sleeve in this alternativeembodiment could be increased, for example, by rotating the imagingsleeve. It will be understood that other embodiments may be provided bycombining the aspects mentioned above, such that one or more imageelements are provide for both longitudinally directed imaging andlaterally directed (e.g. radially) imaging. Furthermore, an alternativeembodiment in which an array of imaging elements are integrated into theimaging sleeve.

The imaging element or elements incorporated into the imaging sleeve mayemploy a wide range of imaging modalities, including, but not limitedto, magnetic resonance MR imaging, ultrasound, optical imaging devices(such as, but not limited to visible 2D-3D imaging), optical devicesand/or conduits for performing optical coherence tomography,hyper-spectral imaging, polarized light imaging, Raman Imaging, andfluorescence Imaging), electrophysiology, photo-acoustic imaging,thermal imaging, electromechanical arrays (strain gauges, ionicconductors), and biosensor arrays.

In some embodiments, the imaging sleeve may have an aperture or openingat its distal portion, such that the operator or clinician may insertitems such as tools or other imaging devices and access internal tissuesexposed through the central bore. In other embodiments, the distal endof the imaging sleeve may be closed at its distal surface by a tissuefixing surface that is transparent or at least partially transparent toimaging radiation associated with at least one imaging modality.

One potential benefit of an imaging sleeve embodiment is the ability tointraoperatively remove an imaging sleeve of a first type or modalityand replace it with an imaging sleeve of a second type or modality. Thisbenefit is not present for the aforementioned embodiments involving anaccess port with integrated imaging elements, in which the choice ofimaging elements is fixed.

1.5 Combinations of Insertable Imaging Devices

In other embodiments, two or more insertable imaging devices may be usedtogether, for example, in order to achieve multi-modal imaging ofinternal tissues. It will be understood that there are wide variety ofcombinations of insertable imaging devices that may be combined togetherto provide different imaging embodiments. The following examples areprovide to illustrate some example implementations of such embodiments,and the scope of the present disclosure is not intended to be limited tothese embodiments.

Some specific examples of combinations of insertable imaging devices aredescribed and illustrated below.

1.5.1 Multiple Coaxial Imaging Sleeves

FIG. 10 illustrates a non-imaging access port 60, and two coaxialimaging sleeves 62 and 64 that are insertable into the access port 60where the two imaging sleeves 62 and 64 may be nested.

1.5.2 Imaging Sleeve(s) and Insert Imaging Probe/Imaging Introducer

FIG. 11 illustrates a non-imaging access port 70, one or more imagingsleeves 72 inserted into the access port (two or more imaging sleevesmay be nested), and one of an insertable imaging probe 20 and an imagingintroducer. Electrical connection to the conductive elements in imagingsleeves 72 may be established using press-fit mechanism 59 described inFIG. 9.

1.5.3 Imaging Access Port and Insert Imaging Probe/Imaging Introducer

In a further embodiment, an access port with integrated imagingelement(s) and one of an insertable imaging probe and an imagingintroducer may be envisioned.

1.5.4 Imaging Access Port and Imaging Sleeve(s) and Insert ImagingProbe/Imaging Introducer

In FIG. 12, an access port with integrated imaging element(s) 76 isshown and one or more imaging sleeve inserted into the access port (twoor more imaging sleeves may be nested), with an imaging probe 20inserted into the imaging sleeve.

1.5.5 Imaging Access Port and Imaging Sleeve(s) and Insert ImagingProbe/Imaging Introducer

In FIG. 13, an exploded view is shown, including an access port 80 withintegrated imaging element(s) 82, an imaging sleeve 82 insertable intothe access port 80 (where two or more imaging sleeves may be nested),and an insertable imaging probe 84.

While the preceding section has introduced several embodiments of thepresent disclosure from a general perspective, the following sectionspresent specific and non-limiting embodiments providing exampleimplementations involving selected imaging modalities or combinations ofimaging modalities. The following section presents example variousimplementations involving magnetic resonance insertable imaging devices.

2. Magnetic Resonance (MR) Insert Imaging Device

The present section describes various embodiments employing one or moremagnetic resonance imaging radio-frequency (RF) coils (e.g. coilelements) for imaging within an access port, cannula, lumen, channel orother such structure, in order to achieve magnetic resonance imagingwithin an internal area of interest.

Some embodiments introduced herein provide insertable MR imaging devicesthat are alternatives to current surface or volume coils, where theinsertable MR imaging devices can be inserted within a cavity to provideimaging of the tissues surrounding the devices and tissues beyond adistal end of the device (end-fire imaging) given its close proximity.The coil's ability to detect signals increases as the coil approachesthe tissue being imaged. RF coils that are local to the tissue ofinterest have a higher signal-to-noise ratio (SNR) than those positionedfurther away, and thereby a higher quality image.

As described above, some embodiments described in the present sectionmay complement a minimally-invasive neurological procedure (such assurgical procedures) whereby a procedure involving internal brain tissueis conducted via a narrow corridor formed via an access port. Forexample, an insertable magnetic resonance imaging device may be adaptedto be received (e.g. slidably received, as described in Section 1 above)into the bore of an access port and exploit its close position toproduce MR images, such as high resolution MR images of the surrounding(lateral) brain tissue and/or forward-looking (anterior, distal)tissues. Such images may be used during medical procedures (e.g.surgical procedures), potentially providing detail that would otherwisenot be obtainable with current technologies (or would otherwise beobtainable with less resolution or signal to noise, using currentlyavailable technologies).

Several insertable MR coil probes known in the art have been designedfor vascular or prostate imaging, where the tissue of interest islocated adjacent (laterally) to the insertable coil. Some embodiments ofthe present section of the disclosure provide insertable imaging devicesthat are suitable for imaging anterior tissues, or both lateral andanterior tissues. Such devices may be useful, for example, inneurosurgical and endo-nasal applications involving an inserted accessport, where it is imperative to receive signals from the tissue residingat the distal portion of an access port.

2.1 Example MR System

FIG. 14 provides a schematic illustration of a magnetic resonanceimaging system that involves an insertable MR imaging device. The mainmagnet of a magnetic resonance imaging scanner generates a magneticfield (B₀) and RF coils are used to generate orthogonal magnetic fields(B₁) for exciting the signals during transmission and receiving the MRrelaxation signals during reception. The main magnet could be, forexample, a solenoid, single-sided magnet, or a dipole array made withsuperconducting wire, high temperature superconducting (HTS) wire, anelectromagnet, or a resistive magnet, or lastly a Halbach array ofpermanent magnets.

The example system includes an insertable MR imaging device, which maybe, for example, an insertable MR imaging probe, an insertable MRimaging introducer for inserting an access port, an access port with oneor more integrated MR imaging coils, one or more MR imaging sleeves thatare configured to be coaxially inserted into an access port, or variouscombinations of these insertable imaging devices, as illustrated inSection 1. Various example implementations of such insertable MR imagingdevices, and various coil configurations, are described in detail below.

Magnetic resonance imaging can be performed either with separatetransmit and receiver coils, or by using the same coil for transmit andreceive. The transmit coil may be a head coil, body coil, or the probeitself. The reason one tends to use a separate transmit coil is to haveuniform excitation of tissue. However, by using appropriate pulsesequences, it is possible to still obtain reasonable images from anon-uniform T/R coils.

Other elements included in the example MR system, shown the Figureinclude a gradient system consisting of coils, amplifiers, and DACconverters, an RF system which comprises a transmitting and receivingcoil which may or may not be the same device, in addition to DAC/ADC,and amplifiers. Finally, a computer, controller, pulse generator andreconstruction engine are included.

The controller sends the pulse sequence at the correct time, and thereconstruction engine generates the image from the raw data. Thecontroller and the reconstruction engine, while shown as separatecomponents in FIG. 14, may alternatively be integrated in a singledevice.

2.2 Example Electrical Circuit

FIG. 15 schematically illustrates an example implementation of circuitfor receiving signals from a magnetic resonance coil element within aninsertable MR imaging device. The electrical circuit 1500 includes apreamplifier 1501 (or low noise amplifier (LNA) that amplifies thesignal that is generated. Variable capacitors (1502 and 1503) are usedto tune and match the circuit 1500. Diodes (1504, 1505, 1506) are usedto detune the coil (if it is a receive only coil) when the system istransmitting. One or more inductor(s) (or RF chokes) 1507 are used toseparate DC control signals from the RF path.

An example of a circuit 1500 for receiving signals to a magneticresonance coil is shown in FIG. 15. In the example embodiment shown, acoil element (e.g. a single coil or a coil element of an array of coilelements) is connected and matched to a low-noise preamplifier, whichwill amplify the received signal for processing. These channels may beconnected using a 50Ω coaxial cable (15.8) that carries the ac signal toand from the preamplifier. The preamplifier, itself, may be poweredthrough a set of discrete wires. In this diagram, the coil is connectedto the two arrows. A coax connection could be made here with the outsideof the connector at the bottom and the center line at the top,alternatively a pair of wires could be used, or a twinax line, or atwisted pair, or a direct connection to the coil.

The circuit may contain an active and passive detuning diode to ensurethe coil is non-resonant at the Larmor frequency during the transmissionphase of the MRI. The passive diode is activated by the transmittingfield while the active diode is powered through the centerline of theaforementioned coaxial cable.

The coil must be tuned to the resonant frequency of the system. Avariable capacitor is typically used for this purpose because it iseasily adjusted. However, a fixed capacitor could alternatively be used.Secondly, to achieve the lowest noise figure, the preamplifier has anideal source impedance. Another variable capacitor is used to vary thesource impedance so that this impedance is achieved. Again, afixed-value capacitor could be used for this purpose. The inductor isused to as an RF choke to separate the control signals (such as acommand to block during transmit) from the RF path.

It is noted that not all of the components would need to reside withinthe probe body—some could reside within the handle.

It is noted that the circuit shown in FIG. 15 is but one examplecircuit. There are alternate methods to noise match the preamplifier(such as using inductors, multiple capacitors, multiple inductors,transformers, transmission lines, etc), alternate methods to detune thecoil (such as PIN diodes, switches, FETs, MEMS devices), alternatemethods to shield the control signals from the RF line (such as PINdiodes, switches, transmission lines).

Although FIG. 15 illustrates a single circuit that is connectable to asingle coil, it will be understood that in embodiments in which the MRimaging device includes an array of coil elements (i.e. multiplechannels), the circuit shown in FIG. 15 (or an alternative circuit) maybe included for each coil element in the array.

2.3 Insertable MR Imaging Probes

In some embodiments, the insertable MR imaging device is an insertableimaging probe, as described in Section 1.1 above, where the imagingelements are one or more MR coils.

2.3.1 The Probe Housing

In embodiments in which the MR imaging probe is configured to be usedwithin a MRI scanner, employing the scanner to provide the primary B₀field, the probe housing constructed from an MRI-compatible material.Examples of MRI-compatible materials include polycarbonate, Teflon,Delrin and PEEK.

The dimensions of the insertable imaging probe may be selected such thatthe probe may fit within a pre-selected access port, as described inSection 1.1. However, it is to be understood that the MR imaging probeintended to be limited to applications involving the use of an accessport, and may additionally or alternatively be used outside of an accessport in any in-situ or ex-situ applications where appropriate. Forexample, MR imaging probe embodiments according to the presentdisclosure may be employed for local imaging during an open craniotomy,endonasally, or when examining sample tissue. In some non-limitingexample embodiments, the diameter of the MR imaging probe can range froma diameter from less than approximately 1 mm to 13 mm, and with a lengthof less than approximately 1 mm to 100 mm.

In some embodiments, at least one portion of the MR imaging probe may bedisposable and/or sterilizable, as described in Section 1.1. Forexample, the disposable and/or sterilizable (e.g. autoclavable) portionof the insertable MR imaging probe may be connectable, via a lockingmechanism, to a handle that is used to position the MR imaging probe asrequired. This handle, which may or may not be disposable, may alsoserve to store electrical components and/or to route cables back to theMRI system as a whole. Incorporating some or all of the magneticresonance circuit elements within the handle of the probe enables a slimsilhouette of the body portion of the MR imaging probe.

As described in Section 1.1.1, in some embodiments, the electrical andimaging components contained within the MR imaging probe may be dividedinto two groups: components that are housed within the handle, andcomponents that are housed within the insertable and optionallydisposable body portion of the insertable imaging probe. In someembodiments, at least some of the electrical components of the MRinsertable imaging probe are housed within the handle, while othercomponents, such as other electrical components and imaging elements orimaging assemblies, are housed within the disposable body portion. Forexample, at least some of the electrical components, such as at leastsome components of the tuning and matching circuit, or preamplifiercircuit, may be housed within the handle portion, while othercomponents, such as one or more electrical coils, may be housed withinthe body portion of the insertable imaging probe.

Some example configurations for the integration of electrical componentsinto the handle of a MR imaging probe are as follows. In one example,only the wire portion of the coil resides in the probe body, while theremainder of the components reside in the handle. In another example,the coil wire and tuning capacitors reside within the probe body, whilethe matching components and preamplifier(s) reside in the handle. Inanother example, the coil wire, tuning capacitors, and matching circuitsreside within the probe body, while the preamplifier(s) reside withinthe handle. Finally, in another example, all components may be housedwithin the probe body. In embodiments in which one or more componentsare integrated into the handle, for use with a disposable orinterchangable probe body portion having one or more integrated coils,the tolerances on the capacitors housed within the handle portion couldbe specified to be sufficiently low or tight.

Some MR imaging probe designs according to embodiments provided hereinserve to excite or receive a B₁ field substantially perpendicular withthe main B₀ field, as generated by the main magnet, to acquire a high ormaximum signal potential. It is possible that the alignment of the portcoil with the main magnetic field changes with operating conditions, forexample, the angle of the operating corridor. For this reason, the MRimaging probe may be made available in varying coil geometries toaccommodate operating conditions and magnetic field orientations. Thevarious coil configurations described below provide several non-limitingexample implementations of such different coil geometries.

In some embodiments, the handle portion of the MR imaging probe may bereusable, and may be configured to mate with a variety or disposableand/or sterilizable body portions having different coil types ofgeometries.

2.3.2 Markings on Coil Housing and/or Handle

As noted in Section 1.1.2, the body and/or handle portion of the insertimaging probe may have delineated markings, for example, with graduatedmeasurement markings to provide depth information (perception) whenguiding the port into the cavity.

In addition, a ‘B₀’ marking may be provided, which can be employed toensure the probe is positioned with proper electromagnetic fieldalignment. Aligning the B₀ marking on the MR imaging probe with theknown direction of the B₀ field of the scanner (e.g. axially within thebore of the scanner) will ensure that coil elements within the MRimaging probe will be receiving and/or transmitting fields orthogonal tothe B₀ field of the scanner as shown in FIG. 37.

2.4 Coil Configurations and Geometries

The coil designs presented below are provided as example andnon-limiting implementations of potential coil configurations. Some ofthe following embodiments provide coils that are configured to produce aforward-looking focused receiving or transmitting zone. In other words,some of the following embodiments provide coil configurations that aresensitive to regions anterior to the longitudinal probe body (regionsbeyond the distal end of the probe body), e.g. in an end-firedconfiguration beyond the distal region of the body of the imaging probe.Such embodiments may be included or incorporated within the various MRimaging probes described within this disclosure.

The coils themselves may be formed from a conductive material, forexample copper, silver, silver coated copper wire, super conducting wireor tape, high temperature superconducting wire or tape, carbonnanotubes, or graphene, that may or may not be cooled (to lower metalresistivity and hence increase SNR) during image acquisition. Whereneeded, a dielectric substrate may be used. Suitable dielectricmaterials may be materials such as polyurethane, polycarbonate, Teflon,air, foam, FR4, liquid crystal polymer (LCP), low temperature cofiredceramics (LTCC), or high temperature cofired ceramics (HTCC), amongothers.

It will be understood that the MR coil may be provided according to anumber of different configurations and fabrication methods. For example,the coil may be formed from wire and wound. Alternatively, the coilcould be thick film conductor, and screen printed. In othere examples,the coil could be tape and adhered to a surface. In other examples, thecoil metal may be sputtered or machined away from a block of metal,etched, or formed using EDM.

2.4.1 Folded Stripline

The first example embodiment is based on the stripline resonator, and isillustrated in FIGS. 16 A-C. This stripline generates a B₁ field (or, asa receive-only coil, is sensitive to magnetic fields) in the xdirection.

The stripline, having a folded configuration, focuses the imaging regionin an end-fire direction (e.g. in a region beyond the distal extent ofthe coil, as shown in the Figure.

As seen in FIG. 16A, this stripline coil is electrically shortened withcapacitors (CO to a half-wavelength in dimension where the wavelength isakin to the aforementioned Larmor frequency. A matching capacitor(C_(m)) is used to match the stripline to the amplifier. This structureis advantageous given its low-profile design, and high adjacent SNRcapability.

The stripline may be constructed from conducting material that is foldedabout a dielectric substrate containing a ground-plane, also made fromconducting materials.

The signal line and the ground line should be separated by somematerial, such as a dielectric, or other insulator. The dielectric canalso be used to insulate the outer conductors from the patient. In thisfigure, the dielectric is between the conductors, as well as on theoutside of the outer conductors. The figure shows a side view of thestripline inside a cylinder. It is configurable within a cylinder. Theelectrodes are close to the surface of the probe body.

To feed the stripline, two example approaches are considered: the firstembodiment employs a series capacitor to match the feedline to 50Ω (orany desired impedance), as shown in FIGS. 16B and 16C. The secondembodiment varies the location of the feed point to achieve a 50Ω match(or any desired impedance) and does not use a matching capacitor(C_(m)). In this embodiment, the outer conductor of a coax line may be(though is not required to be) electrically connected to the groundconductor of the coil to avoid floating conductors when connecting thefeedline.

It will be understood that any or all the electrical components (e.g.capacitors, diodes, amplifiers, RF inductors) from the conducting stripsused for the stripline may be contained within the handle portion of theinsertable MR imaging probe. This configuration allows for a low-costdisposable embodiment to be provided, where the electrical componentsare located in a re-usable “handle” portion and connected to adisposable (or sterilizable) body portion. Two example implementationsof this embodiment are shown in FIGS. 17A and 17B.

In FIG. 17A, the handle is on the left, the removable portion is on theright. The connections can be made with coax connectors such as SMA, N,F, microcoax, SMB, pin and socket, press contact, springs. The preampcould be located in the handle (as in FIG. 17B), or even further removedfrom the imaging coil and not in the handle. However, putting the preampcloser to the antenna can improve performance by increasing SNR.

In some example implementations, the width of the stripline can varyfrom less than approximately 1 mm to greater than 13 mm, while thelength of the folded stripline can measure from less than 1 mm togreater than 100 mm. The value of the tuning capacitors C_(t) willchange as the length is varied, because the length of the antennacorresponds to inductance, and the capacitors are required to resonatewith the inductance. One skilled in the art will know to vary thecapacitor value as the length is varied.

It will be understood that there are many possible configurations of thestripline resonator based coil. The following sections illustrate someadditional example implementations that involve coils based on multiplestriplines.

2.4.2 Folded Quadrature Striplines

A quadrature coil is sensitive to two orthogonal polarizations ofmagnetic field. FIG. 18 presents an example of two folded striplinecoils as a quadrature pair. One of the striplines generates (or issensitive to) a B₁ field in the x direction and the other in the y. Thefour capacitors shown in the figure are tuning capacitors. The centerline is connected to ground. While the striplines both fold over eachother at the distal end of the probe, there is no electrical connectionmade between the striplines at this point. The only electricalconnection between the striplines is the common ground that they share.

To connect to tuning and matching circuitry, a ground connection wouldbe attached to the center line. A matching circuit would be attachedeach of the circle-dot connections. The matching circuit could be amatching capacitor, or inductor, or phase shifting network, followed bya preamplifier. The end of the probe is at the other end of thecapacitors.

It is to be understood that the number of striplines used herein mayvary. These striplines are depicted as sharing a common ground planewithin the center of the coil, however, in other embodiments, thestriplines may have separate ground planes.

2.4.3 Distal Stripline Arrays

FIGS. 19A-C illustrate additional embodiments where stripline resonatorsare provided at or near the distal portion of the MR imaging probe,either in a linear or radial formation. In each of these embodiments,the receiving or transmitting region associated with the coil array liesbeyond the distal region of the MR imaging probe.

The common ground is a solid, circular ground plane underneath eachstripline. The depth is somewhat exaggerated in this figure. The outputswould be combined as a phased array to obtain the full image. In FIG.19A the array of striplines is sensitive to a magnetic field in the ‘x’direction. In FIG. 19B, the array is sensitive to the ‘y’ direction.There are several possible methods (previously described) to feedstriplines. In FIGS. 19A and 19B the feeding method is as per FIG. 16C.Preamplifiers and the remainder of the magnetic resonance imaging systemare not shown.

In the radial arrangement, shown in FIG. 19C, the striplines are allabove a common ground plane. In this example figure, 4 striplines areshown, each with a pair of tuning capacitors to adjust the resonantfrequency. The striplines are not making electrical contact, and areseparated vertically. The striplines are fed as per FIG. 16C. Again, notshown are preamplifiers or any further elements of a magnetic resonanceimaging system. The output from each stripline are combined to form animage as a phased array coil.

2.4.4 Loop Coils

FIGS. 20A-D illustrate various example implementations of a loop coil.The loop coil may be beneficial given its high Q, accompanying high SNR,and versatility. In FIG. 20A, a loop is oriented sideways in a probe.The distal end of the probe is into the page, and the feeding locationis at the location of the semi-circle. Two capacitors (Ct and Cm) areused to tune the loop to the appropriate resonant frequency. Not shownare any additional matching components that would be used to noise matchthe loop to a preamplifier. Also not shown are any preamplifiers whichcould be located separately (or, alternatively, formed within theprobe). The feedpoint is located across Cm.

In FIG. 20B, a folded loop locates the fold at the tip of the probe toallow for the maximum forward looking sensitivity. Two capacitors (Ctand Cm) are used to tune the loop to the appropriate resonant frequency.Not shown are any additional matching components that would be used tonoise match the loop to a preamplifier. Also not shown are anypreamplifiers which could be located separately (or, alternatively,formed within the probe). The feedpoint is located across Cm.

A loop coil may be included within the tip of a probe, as in FIG. 20C.This loop could have varying diameters to increase the intensity of theforward-looking imaging region. The diameter of the loop may range frommicrometers to centimeters. The loop coil may be constructed fromconducting material, as previously outlined, and may be backed by adielectric substrate. In FIG. 20C the loop is tuned with capacitiveelements (such as Cm and Ct), and is fed across capacitor Cm. Not shownare any preamplifiers which could be located separately (or,alternatively, formed within the probe).

Loop coils may be used in an array, and may be decoupled from otherelements within the array either geometrically or with capacitive orinductive components.

FIG. 20D shows a two-turn coil, oriented sideways within a probe. Thetwo-turn loop coil uses capacitors Cm and Ct to tune the coil to theresonant frequency of the system. The feedpoint is located acrosscapacitor Cm. Not shown are any preamplifiers which could be locatedseparately (or, alternatively, formed within the probe). It will beunderstood that in alternate embodiments, any number of turns may beemployed.

FIGS. 21A-B illustrate example coil loop implementations involving (A)two and (B) four folded loop coils that are provided at or near thedistal portion (e.g. the tip) of the MR imaging probe in order toenhance the forward looking aspect of the probe.

In FIG. 21A, two folded loops arranged so that their folds are locatedat the distal end of a probe to maximize their forward lookingsensitivity. The two loops are overlapped so as to cancel their mutualinductance to decouple the two loops. There is no electrical connectionmade at the overlap. It is also understood that in alternateembodiments, capacitors of inductors could be used to decouple theloops. Each of the loops is equipped with a pair of capacitors fortuning and a feeding location. Not shown are any noise matchingcircuits, or any decoupling diodes, or any preamplifiers that might beused to amplify the signal. The feedpoints for each loop are locatedacross capacitor Cm.

FIG. 21B is similar to FIG. 21A showing 4 loops. Again, all loops areoverlapped to decouple them, without forming an electrical connection.As in FIG. 21A, other decoupling methods are possible, such as usingshared capacitors, or inductors. Each loop is equipped with a pair ofcapacitors for tuning as well as a feeding location. Not shown are anynoise matching circuits, or any decoupling diodes, or any preamplifiersthat might be used to amplify the signal. The folded ends are located atthe distal end of the probe.

2.4.5 Butterfly Coils

In some embodiments, one or more coils of the MR imaging probe may beprovided in a butterfly coil configuration. For example, butterfly coilsmay be provided within the MR imaging probe in a planar configuration orin a folded configuration (to improve the forward-looking imagingaspects of the coil). Example implementations of butterfly coilconfigurations are, shown in FIGS. 22A-C.

FIG. 22A shows a butterfly, or figure-8 coil. Here it is shown locatedalong the length of a port. Two capacitors, Cm and Ct, are used fortuning the coil to the appropriate resonant frequency, and the feedinglocation is indicated by the semicircle. This coil will be sensitive toareas above and below it. Not shown are any noise matching components,control signals, detuning elements, or preamplifiers. FIG. 22B alsoshows a folded butterfly coil. The fold is located at the distal end ofthe probe to maximize the forward looking area. No electrical connectionis made at the fold location. Two capacitors, Cm and Ct, are used fortuning the coil to the appropriate resonant frequency, and the feedinglocation is indicated by the semicircle. Not shown are any noisematching components, control signals, detuning elements, orpreamplifiers.

FIG. 22C shows a butterfly coil with two turns of wire. Two capacitors,Cm and Ct, are used for tuning the coil to the appropriate resonantfrequency, and the feeding location is indicated by the semicircle. Thiscoil will be sensitive to areas above and below it. Not shown are anynoise matching components, control signals, detuning elements, orpreamplifiers. No electrical connection is made between the two turns ofthe coil, save through the capacitors Cm and Ct.

As with other coil geometries described here, the coil dimensions may bescaled from micrometers to centimeters (e.g. from approximately 1 micronto approximately 1 cm) in diameter and micrometers to centimeters inlength.

The butterfly coil may have any number of turns, and may be positionedeither radially surrounding the port, such that each butterfly isrotated around the axis that runs along the length of the port or alongthe length. The coil butterfly is constructed from a conducting materialand may be formed upon a dielectric substrate. As noted above, the probematerial should be formed using a material with a good susceptibilitymatch to water. The butterfly coil may be decoupled from other elementsin a coil array through geometric positioning or capacitive/inductiveelements.

2.5 Arrays

The preceding embodiments described several example implementations ofcoil configurations that may be employed in an insertable MR imagingdevice, such as an insertable MR imaging probe. It will be understoodthat coils according to these configurations, or according to variationsthereof, may be provided in an array form.

2.5.1 Sparse and Dense Arrays

In some embodiments, an array may be formed by providing, on or withinan insertable MR imaging device, a plurality of coils in a prescribedspatial arrangement. The array of coil elements which combine to formthe port coil may be provided according to many different embodimentswithout departing from the scope of the present disclosure. Exampleembodiments feature an array of RF elements to enable parallel imagingwhere the sensitivity of each element is used to accelerate imagingtimes. These arrays may be used as receive-only, transmit-only, or incombination as a transceiving device. In transceiving mode, anelectrical switch is included in order to toggle between the receivingand transmitting circuits. Examples involving parallel imaging includeasymmetric g-factor, using phase encoding in one direction, drivinggradients in opposite direction.

In some embodiments, the array may be a dense array (e.g. a high-densityarray). As used herein, the phrase “dense array” refers to an arrayhaving a relative spacing between neighboring array elements of lessthan approximately 1 mm and the phrase “sparse array” refers to an arrayhaving a relative spacing between neighboring array elements of greaterthan approximately on the order of 1 cm. For example, FIG. 25illustrates an example implementation of an insertable MR imaging probehaving a dense array of striplines.

In some embodiments, the array elements of a dense array may form aphased array. In a phased array, each coil has a spatially separateregion of sensitivity.

Within the array, each element may be tuned to the Larmor frequency ofthe nuclei under investigation using non-magnetic capacitive componentsas required. These elements may have multiple tunings to enablecollecting data from numerous nuclei. The desired tuning can be selectedactively by way of an electronic switch that includes the appropriatetuning capacitors within the circuit. The Larmor frequency isproportional to the applied magnetic field strength, and as such, theimaging array can be designed to operate at varying field strengths,whether it be a low-field or high-field application. To maintainisolation between the channels corresponding to various coil elements,the coil elements are decoupled from each other, for example, eithercapacitively, geometrically, or inductively within the circuit. Theplurality and placement of the capacitive and/or inductive elements aredictated by individual coil geometries. Where appropriate thesecomponents may be placed in the handle.

In one embodiment, the imaging device may include a dense array of MRIreceiver coils, such as an array of stripline coils as in FIGS. 19A-C.In another example implementation of an array configured for end-fireimaging, an insertable MR imaging probe may include an array of multipleloop coils, as shown in FIG. 27. In this manner, a forward-lookingimaging field can be imaged, for example, with a high sensitivity, andwith the ability to cover the field of imaging using many small arrayelements, which enables parallel imaging.

2.5.2 Combinations of Different Coil Configurations and Geometries

In addition to the aforementioned embodiments involving single andmultiple coils of a given type, it will be understood that in otherembodiments, a MR imaging probe may include multiple coil types, forexample, to form a coil array.

For example, in some embodiments, two or more of loop coils, striplines,and butterfly coils can be combined within a MR imaging probe. In someembodiments, the coils that are combined may include one or more foldedcoils to generate an end-fire focused imaging area. The proceedingsection presents several non-limiting examples of such combinations. Itwill be understood that these examples are non-limiting and that otherconfigurations may be obtained by alternative combinations of two ormore coil types.

An example in which the three aforementioned coil types are providedtogether in a geometrically decoupled fashion is shown in FIG. 23. Theconductor may be a wire, or a planar conductor, etc. This arrangement isparticularly attractive given that it generates B₁ fields (or issensitive to a varying magnetic field) in x, y, and z. Therefore, thiswill provide a high resolution forward looking image regardless of itsorientation with respect to the main magnetic field. The distal tip ofthe probe is into the page, as indicated by the arrows. All of thesecoils are inherently decoupled by being sensitive to orthogonal magneticfields. FIG. 23 shows a separate view of three orthogonal coils that canbe combined within 1 imaging probe. Coil ‘A’ shows a folded butterfly(as in FIG. 22B) sensitive to fields in the ‘y’ direction, coil ‘B’shows a folded stripline coil (as in FIG. 6A), sensitive to fields inthe ‘x’ direction, and coil ‘C’ shows a loop coil (as in FIG. 20C)sensitive to fields in the ‘z’ direction. All three of these coils maybe combined in a single imaging probe due to the orthogonality of thefields that they are individually sensitive to.

Another example implementation employs striplines, loops, and butterflycoils that are all arranged to be orthogonal to the B₀ field, as shownin FIG. 24. To allow for multiple channels orthogonal to the B0 field, acombination of coil geometries are used. Six different coilconfigurations are used to image to the left, right, above, below, andforwards of the imaging probe. To image forwards of the probe, coils ‘A’and ‘B’ are used (folded stripline (‘A’) and loop (‘B’)), to image tothe left of the probe, coil ‘C’ (sideways loop orientation), to image tothe right of the probe, coil ‘D’ (sideways loop orientation), to imageabove the probe coil ‘E’ (butterfly oriented along probe), and to imagebelow the probe, coil ‘F’ (butterfly oriented along probe). All thesecoils can be combined in a single imaging probe.

Adding more coils can improve performance. This arrangement uses twoloops to look left and right, two butterflies to look up and down, and aloop and stripline at the tip. The end of the probe is located witharrows.

The coils are designed to receive signals along the x and z directions,and the coils are intended to be orientated such that the external B₀field is directed along the y axis (based on appropriate orientation ofthe MR imaging probe, for example, according to a field orientationmarker on the probe handle and/or probe body). Although 6 coils areshown in the FIG. 24, it will be understood that there are many suchpossible arrangements that may be achieved without departing from thescope of the present disclosure.

FIG. 27 illustrates an example embodiment in which an array of coils isprovided at the distal end of an insertable imaging probe. Although thefigure shows an array of loop coils, it is to be understood that anarray of other coil types could be used, such as an array of striplines,butterfly coils, or any combination thereof.

FIG. 28A illustrates an example embodiment in which a stripline coil isprovided in quadrature with a butterfly coil located at the distal tipof a probe. The butterfly coil is tuned with capacitors Cm and Ct. Thefolded stripline is tuned with capacitors Ct and matched with capacitorCm. The folded stripline is sensitive to fields in the ‘x’ direction,while the butterfly coil is sensitive to fields in the ‘y’ direction.This orthogonal sensitivity allows the coils to be inherently decoupled.Not shown are any preamplifier, or decoupling diodes.

FIG. 28B illustrates an example embodiment in which a butterfly coil isprovided in quadrature with a loop coil located at the distal tip of aprobe. The butterfly coil is tuned with capacitors Cmb and Ctb, the loopis tuned with capacitors Cm and Ct. The butterfly coil is sensitive tofields in the ‘y’ direction while the loop is sensitive to fields in the‘z’ direction. This orthogonal sensitivity allows the coils to beinherently decoupled. Not shown are any preamplifier, or decouplingdiodes.

In FIG. 29, an array of stripline coils are placed parallel to the axisof the probe. The stripline coils may be placed equi-distant apartaround the circumference of the imaging probe. Not shown are tuningcapacitors from each stripline to a central ground at the proximal endof the probe, also not shown are the matching circuit (which could takeeither forms described above) or preamplifiers, or blocking diodes.Using an array of striplines allows the coil to obtain higher SNR in theareas immediately next to the imaging probe, though this geometry ismore sensitive radially than forward looking.

Another example embodiment is illustrated in FIGS. 30 and 31 in whichstriplines in an array are overlaid with loop coil configurations.Stripline coils and loop coils are inherently decoupled. FIG. 30illustrates a stripline coil and loop coil combination configuration. Inthis figure, the stripline is sensitive to a field in the ‘x’ directionwhile the loop is sensitive to a field in the ‘z’ direction. Not shownare tuning/matching circuits, preamplifiers, blocking diodes, etc. Thestripline requires a ground circuit (not shown). FIG. 31A illustrates analternate embodiment where each stripline coil is overlaid with a loopcoil to form an array. Not shown are tuning/matching circuits,preamplifiers, blocking diodes, etc. Each stripline may have a groundbelow it, or all striplines may share a common ground. FIG. 31B is afurther elaboration of FIG. 31A that illustrates an exemplary arraycircuit that indicates the use of decoupling capacitors (Cd) betweenelements of a planar stripline array. Each stripline is tuned with twocapacitors (Ct) and fed as per FIG. 16C. Each stripline may have aground, or they may all share a common ground plane (not shown).

2.5.3 Increasing Parallel Imaging through Automatic Coil Detection

In some embodiments, the insertable MR imaging probe may be employed forparallel imaging, which is a technique used in MR to reduce theacquisition time. This is accomplished by providing multiple receivingcoils, each receiving signals from a slightly different spatial area.Parallel imaging may be performed in either the slice direction, thefrequency direction, or the phase encoding direction.

Parallel imaging will be most effective when the body portion of theprobe is oriented such that the phase encoding direction of the scanneris perpendicular to the axis of the striplines. However, due to thevariances of neurosurgery, the direction of the port often cannot beknown in advance, nor can it be fixed.

To still allow for maximum parallel imaging, a navigation system can beused to track the location of the port relative to the patient, and thescanner can then choose an oblique slice. Typically, in MR scanners, thescan planes are chosen in standard orthogonal planes, i.e. axial,sagittal, and coronal. However, it is possible to scan in any plane(referred to as an oblique plane) by choosing the gradients correctly.In order for the scanner to know the direction of the port, the portcoil must be tracked, typically by optical means.

An MR image typically has two axes—the frequency axis, and the phaseaxis. Parallel imaging can be used (but not exclusively) to speed up thetime of acquiring the phase axis. The frequency axis and the phase axiscan correspond to a real axis, such as ‘x’, or ‘y’, or ‘z’, or anyarbitrary direction. If an array of coils was placed in a scanner suchthat each coil was arranged on a line that did not correspond to thescanner's definition of ‘x’, ‘y’, or ‘z’, it could be advantageous todefine an oblique reference plane so that the axis of the coils does liealong this plane. This will allow maximum time improvement usingparallel imaging. The combination of knowledge of the port's orientationobtained from an optical tracking system with the knowledge of thescanner's reference planes will allow a user to vary the scan parameterssuch that the oblique angles chosen by the scanner maximize the parallelimaging capacity.

2.5.4 Rotatable Forward-Looking Coil Element

In another embodiment, the forward-looking imaging capability of an MRinsertable imaging probe may be extended by providing a means ormechanism for rotating the tip of the coil.

An example of this is shown below where a swiveling tip housing the coilelements rotates to increase the imaging angle. For example, the coilelements may be enclosed within a rotating head 3202, as shown in FIG.32. FIG. 32 shows in example implementation of an insertable MR imagingprobe having a swiveling tip housing the one or more imaging elements,where the tip rotates to increase the imaging angle. The mechanism couldbe a physical connection such as a set of gears, or pulleys, or pullingcables.

Another example option depicted demonstrates that by creating a jointbetween the body of the port coil and its tip, or an articulatedmechanism 3302 or wrist as shown in FIG. 33. FIG. 33 illustrates anexample implementation in which the probe tip includes a wrist such thatimaging elements within the tip can rotate about to image at varyingangles. The elements within the tip can rotate about to image at varyingangles, which may allow the probe to be employed to acquire highresolution images of a larger end-fire area about the port, resulting insuperior imaging and increased imaging penetration.

Variable bending of the port tip can be also achieved through the use ofoppositely placed cables located along the wall of the bendable portion.Such an insertable MR imaging probe can also have an orifice along theaxis to allow the introduction of surgical tools through this accesspoint. This embodiment may be used within a surgical channel and isparticularly attractive to image endo-nasally.

FIG. 34 illustrates an example implementation of an insertable MRimaging probe in which variable bending of the probe tip is achievedthrough the use of oppositely placed cables located along the wall ofthe bendable portion. As shown in FIG. 34, cables are inserted throughthe probe wall. The cables are securely attached to the distal end ofthe probe, but not to the proximal end. With a flexible housing, whenone cable is pulled with greater force than the other, and the proximalend of the probe is fixed, a bending motion is achieved. If more than 2cables are used, motion in two directions can be achieved. With 2cables, motion is in one dimension only.

It should be noted that the same functionality of scanning a broad rangeof angles through the end-fire area can be achieved with a rigid probewith one wrist and one elbow joint. The joints can be actuated usingelectromechanical actuators or mechanical actuators such as gears,cables and pulleys.

Although the present embodiments, with a rotating or swiveling distalportion of the probe, pertain to insertable MR imaging probes, it willbe understood that they may be extended or adapted to insertable imagingprobes employing other imaging modalities, such as optical andultrasound imaging.

2.5.5 Insertable MR Imaging Probe with Expandable Forward-Looking CoilElements

FIG. 35 shows an example embodiment of an insertable MR imaging probehaving a forward-looking (e.g. end-fire) configuration, where the distalregion of the probe body includes one or more expandable coil elements.As shown in FIG. 35, the coil elements may be housed within a balloon orinflatable/expandable pouch. In one example implementation, onceinserted, the balloon may be expanded to create a region, for example,of up to 5 cm in diameter, in order to accommodate the expanding coilstructure.

The example embodiment shown in FIG. 35 shows a loop that is constructedfrom a non-rigid subsection of the conductive materials described hereinand attached to mechanical arms that serve to open the coil up to itsfull size within the ballooned region. In doing so the forward-lookingimaging depth of penetration is increased. Any flexible conductivematerial could be used for the coil. This could be, for example, wire,cable, or any flexible tape. In FIG. 35, the loop is shown tuned withtwo capacitors Cm and Ct, and fed across capacitor Cm. Not shown are anypreamplifiers, blocking diodes, or other elements of the magneticresonance imaging system.

2.6 Access Ports with Embedded Coils

The preceding embodiments of Section 2 have disclosed various exampleinsertable MR imaging probes. In several of the forthcoming portions ofSection 2, alternative embodiments are described in which one or morecoils (e.g. coil elements) are formed on or within an access port, or asleeve that is insertable into an access port, as initially described inSections 1.3 and 1.4.

In one embodiment, one or more coil elements are formed on, or embeddedwithin, an access port, thus providing a hollow imaging sleeve whereininstruments such as surgical tools can be inserted during a medicalprocedure. This provides an entry point for other imaging devices, MRguided therapies, or contrast agent administration. This may includebiopsy tools, deep brain stimulation devices, thermal imaging equipment,or ultrasound devices among others.

FIGS. 36A-36D illustrates embedding the coils in the side walls of theport. Here, instead of the resonant microstrip lines of the previousembodiment, this uses coplanar waveguide as the resonator. Coplanarwaveguide is a type of transmission line where the ground and signallines are arranged side-by-side in the configurationground-signal-ground. This allows for a channel to be open within theport. This technique is compatible with the previously mentioned abilityto locate some components within the handle, and some within the portitself. In FIG. 36A, all tuning, matching, and receiving equipment islocated within the handle, and attached when it is time to scan. Thehandle makes electrical connection with the signal and ground linesindicated in FIG. 36A.

In FIG. 36B, the coil communicates wirelessly with the scanner,eliminating the cable from the port coil to the scanner. In order toachieve this, further circuitry is required to upconvert the signal, andto transmit at a frequency different from the larmor frequency using alocal antenna. A further antenna is required to receive the signal, andfurther electronics are required to downconvert and amplify the signalbefore passing the signal to the MR receiver.

FIG. 36C shows a detail of FIG. 36A indicating how the connection fromhandle to probe is made. Contacts are made at all ground and signalconnections, and tuning, matching, and receiving elements are containedwithin the handle portion, as described earlier.

FIG. 36D describes a detail of FIG. 36B indicating possible locationsfor a receiving antenna to be used in a wireless coil setup. In thisexample, one antenna is located within the handle of the port coil, andanother, receiving antenna, is located at the far end of the magnetbore. However, there are many possible antenna locations that would alsoaccomplish the same objective.

The embodiments below illustrate a non-limiting set of other exampleimplementations of access ports with integrated imaging coils.

2.6.1 Examples of Access Ports with Integrated Coils

FIGS. 38A-D illustrate various example implementations of access portswith integrated MR coil arrays. FIGS. 38A-C indicates 3 example imagingprobes that allow for access ports. In FIG. 38A, a folded coplanarstripline coil (as described above) is shown. In FIG. 38B, a sidewayslooking loop coil is shown. In FIG. 38C, a loop is show at the tip ofthe probe, with an open channel through the center of the loop. Further,all of these examples from FIGS. 38A-C, could be combined with othercoils to form arrays.

FIG. 38D illustrates an access port with two side loops and an end loopconfiguration with the coils embedded within the walls of handle, givingan access port through the center, as well as visualization to the left,right, and forwards of the imaging probe.

A central ground is not required for a stripline coil if it is formed asa coplanar waveguide (type of transmission line). In this version, theground, instead of being below the signal line, is located to the leftand right of the signal line.

2.7 Intermediate Imaging Sleeve Insertable into Access Port

In other embodiments, an imaging sleeve with one or more integrated MRcoils may be provided, where the imaging sleeve is insertable into anaccess port, thereby providing a reconfigurable and optional means ofport-based-imaging while still providing a central bore that providesaccess (direct or indirect) to internal tissues. This embodiment wasintroduced in Section 1.4.

In one embodiment, one or more coil elements are formed on, or embeddedwithin, a sleeve that is slidably received within an access port, thusproviding a hollow imaging sleeve wherein instruments such as surgicaltools can be inserted during a medical procedure. All the geometrieswith hollow openings are applicable here.

2.8 Embodiments with Combinations of Multiple Insertable MR ImagingDevices

Finally, it will be understood that, as described in Section 1.5 (and inSections 1.5.1-1.5.5), additional embodiments may be provided bycombining two or more of the above insertable imaging devices.

For example, in one example implementation, an insertable imagingapparatus may include one insertable imaging device that includes anarray of integrated lateral imaging elements, and another insertableimaging device that includes an array of imaging elements that areoriented for forward-looking (end-fire) imaging.

An example of such an embodiment is shown in FIG. 39, which illustratesan insertable imaging apparatus including an access port 92 with anarray of laterally oriented MR coil elements 94, and an insertable MRimaging probe 90 having one or more forward-looking (end-fire) MR coilelements 96. In a cylindrical coordinate system, the insertable MRimaging probe is employed to perform imaging in the ‘z’ direction, whilethe access port with integrated imaging elements is employed to performimaging in the ‘θ’ and ‘r’ directions.

Some imaging elements may be contained in the outer access sheath,however most of the body of the imaging device will contain the imagingreceivers and probes. By placing the imaging devices in closeproximately to the surgical volume, a very high signal to noise ratiocan be obtained for all modalities.

It will be understood that a wide range of combinations of insertable MRimaging devices (probes, access ports, and imaging sleeves) may beemployed without departing from the intended scope of the presentdisclosure. Many such combinations are described in Sections1.5.1-1.5.5.

2.9 Example of Tested MR Imaging Probe Using Stripline Geometry

The present section describes an example implementation of astripline-based MR imaging probe that was fabricated and tested. Thecoil configuration is shown in FIG. 40. It consists of a foldedstripline geometry with a distal loop, constructed from 4 mm wide coppertape that was adhered to the perimeter of a cannula. This stripline is75 mm long and is shown paired with its ground-plane, in a coplanarformation that also extends the length of the cannula and encircles thetip. The stripline is formed from copper tape, which has a ‘plane’. Thisis the same orientation of the ground. Circuit components were locatedat the proximal end. The coil is sensitive to the left, right, up, down,as well as forward. It is not sensitive backward. In this figure,capacitors Cml and Ctl is used to tune a loop coil, capacitors Ct areused to tune a folded stripline coil. Not shown are preamplifiers,blocking diodes, or other circuitry used.

This stripline was matched and tuned using non-magnetic capacitors andpin diodes were included in the circuit to provide blocking during thetransmission portion of the MR scan. Foam tape was used to isolate thestripline from the ground plane in the areas where they crossover. Thefolded stripline coil was sensitive to fields in the ‘x’ direction andthe loop coil was sensitive to fields in the ‘z’ direction.

FIG. 41 shows an image of a sheep brain acquired with this MR imagingprobe at 1.5 T with a resolution of 0.5 mm by 0.5 mm by 2 mm.

FIG. 42 shows an image of the same sheep brain acquired with the sameresolution using a 32 channel head coil at 3 T. A comparison of theimages emphasizes the clarity achieved at 1.5 T with this port coilembodiment as compared with the noisy 3 T version.

An alternative example implementation of the MR imaging probe as thenfabricated, having coil geometry as depicted in FIG. 40. It included afolded stripline coil in conjunction with a loop coil. The loop coil hada diameter of 10 mm and was positioned at the tip of the MR imagingprobe in order to complement the end-fire stripline element, which alsointrinsically decouples the elements. The coils were spatiallypositioned such that they were intrinsically decoupled.

The loop was formed with 14 gauge silver-coated copper wire and waselectrically isolated from the stripline by a foam dielectric substrate.The 50 mm long stripline was formed with adhesive Copper tape wrappedaround a foam substrate. Both the stripline and stripline ground planehad a width of 10 mm. Non-magnetic capacitors were used to tune andmatch both coil elements. This combination of a stripline and a loopprovided a 360° view of the tissue surrounding the port with a focus onthe end-fire direction.

FIG. 43 and FIG. 44 show a high-resolution image of an approximately 2.5cm by 3 cm broccoli floret acquired with the MR imaging probe embodimentdescribed here and the equivalent image taken with a 32 channel headcoil on a 3 T MRI scanner with identical pulse sequences, respectively.The broccoli was located at the tip of the port coil to highlight thestrong end-fire performance. As shown, the broccoli detail is quiteintricate when imaged with the port coil yet imperceptible with the headcoil. This clearly demonstrates the superior image quality attainablewith the MR Imaging Probe.

2.10 Smart Coils

In some embodiments, coil arrays may be employed as smart coils, wherethe coils are dynamically (adaptively) controlled, such that only aportion of the coil elements of the array are activated or interrogatedduring scanning. It will be understood that the present “smart coil”embodiment pertain to any insertable MR imaging device having an arrayof coils, including insertable MR imaging probes, access ports withintegrated coil arrays, imaging sleeves with integrated coil arrays, orcombinations thereof, as described above.

In one example implementation, this may be achieved by an MR system thatis configured to sample signals the elements of the coil array and todetermine when a pre-selected signal level threshold has been achievedfor each coil. When the threshold has been achieved for given coil, thecoil are employed (e.g. activated or interrogated) for scanning. Thisarrangement allows an insertable MR imaging device to contain coils thatare not necessarily orthogonal to the main magnetic field of thescanner.

FIG. 46 illustrates an example implementation of a smart coil system,showing an insertable MR imaging probe having an array of coil. Thiscoil arrangement consists of a butterfly, loop, and stripline element,which in combination excite fields in the x, y, and z direction. Whenthis coil is inserted into an access port, and into the MR Field, aprescan may be conducted with the MRI system. The coils are sensitive toB₁ fields that are perpendicular to the main magnetic field B₀ willreceive a stronger signal than those with a parallel B₁ field.

These signal values are then employed to determine which coil elementswill be activated and which ones will remain off (or, which ones will beemployed for constructing an image, and which will not).

In one example implementation, a criterion for determining which coilsto activate or interrogate employs a threshold value, wherein, coilsreceiving signal levels that are below a certain value will remain off(or will not be interrogated) during signal acquisition.

An example of one algorithm that would be employed by acontroller/processor in order to determine which coils should beactivated or interrogated is shown in the flow chart provided in FIG.45. FIG. 45 is a flow chart illustrating an example method ofselectively addressing selected coils within a coil array in order toachieve a smart coil array. Flow chart FIG. 45 begins with step 4502where a data signal is received. The data signal (allocated throughchannels) is then compared to a threshold (step 4504). The threshold mayinclude a predetermined noise level or known SNR (signal-to-noiseratio). Part of this comparison is to determine whether the signal isabove the threshold (step 4506). If the result is not above thethreshold, channels that do not meet this threshold are excluded (step4510). If the channels do meet the threshold, then they are combinedwith the signal to form a merged value or image (step 4508). Analternate method may include weighing the worse images lower, but stilluse it to combine in the final image where the weight can be based onthe threshold.

In some example methods, the signals from all coils should be sampledagain after initially having determined a subset of coils to use. Forexample, the sampling may occur at a fixed time interval. Alternatively,the sampling may be based on a detected change in the orientation of theinsertable MR imaging device within the B₀ field, such as, a changeddetected by a tracking system, or a change detected by an inertialsensor associated with the insertable MR imaging device, such as anaccelerometer.

In some embodiments, the coils could be selectively activated orinterrogated according to a number of criteria. For example, criteriamay be based on the signal of one coil compared to some otherstatistical measure associated with the other coils, such as the averagesignal magnitude, or criteria based on the a measure of signal to noiseratio, as opposed to signal strength. In another example embodiment, thesignals to include could also be based on the orientation of the probe,as detected by a tracking system. The tracking system could be optical,RF, or accelerometer based (not claiming the tracking system in thispatent). There could be a sensor such as a Hall sensor that is sensitiveto the orientation of the static magnetic field.

2.11 Insertable MR Imaging Devices with Embedded Heating Elements

In some embodiments, an insertable MR imaging device, having an array ofMR coils integrated therein, may further contain an array of heatingelements, where the heating elements may be interspersed with coil arrayelements in order to generate thermal gradients during the imagingprocess. The heating and imaging cycles can be alternated to avoidinterference between MR imaging elements and heating elements.

2.12 MR Imaging Probe with Magnet

Although the preceding insertable MR imaging embodiments have pertainedto devices that employ the main magnet of an MRI scanner to generate theB₀ field, some alternative embodiments may include a magnet within theinsertable MR imaging device for providing the B₀ field. Such devicesmay therefore be used outside of a conventional MRI scanner, since theyare capable of generating their own B₀ field.

An example implementation of such embodiment is shown in FIG. 47A, whichshows an insertable MR imaging probe containing a magnet within its bodyportion for generating the B₀ field. The magnet could be, for example, acylindrical permanent magnet or electro-magnet, or, for example, aspherical permanent magnet or electro-magnet. In some embodiments, themagnet may be capable of producing different magnetic field strengths.In one example implementation, the magnetic field of a permanent magnetemployed may be at least 0.5 Tesla.

In such a configuration, one can consider the conventional threeCartesian axes of an MRI system instead as axes of a cylindrical orspherical coordinate system, depending on the geometry of the B₀ magnet.For the cylindrical system, the Cartesian x,y,z axes could be replacedwith cylindrical axes r, θ, and z. The main B₀ field would be in the zdirection, decreasing with 1/r̂2 in the r direction.

As shown in FIG. 47A, the internal magnet produces an inhomogeneousmagnetic field. There are several approaches to imaging within such aninhomogeneous field. One example implementation employs gradient coilsto generate spatial encoding in the θ and z directions, as shown in FIG.47B, and extrapolate from the non-uniform B₀ for the r gradient. Thearray of coils in FIG. 47B are used in this example as atransmit/receive coil.

The outside of the permanent magnet is typically coated in anon-conductive coating. Therefore, the gradient wiring may be wounddirectly against the permanent magnet itself. Alternately, a spacercould be placed between the permanent magnet and the gradient coils. Thegradient coils are used to generate spatially varying magnetic fields indirections orthogonal to the static magnetic field. In this case, oneset of gradient coils generates a field in phi (angle, around theprobe), and the other generates a field in z (along the probe). Each setof gradient coils would require an independent gradient amplifier. Thefinal gradient, r, radially away from the permanent magnet, is achievedthrough the natural drop-off in magnetic field strength of a permanentmagnet. It should be noted that the gradients do not need to beperfectly linear, as long as they are known. Provided the spatialpatterns of the gradient coils are well plotted, a modern reconstructionengine can undo any warping that occurs.

In order to reconstruct an image using a permanent magnet, the field ofthe permanent magnet, as well as the fields generated by the gradientcoils would need to be accurately known. This could be generated throughmeasurement, or through simulation. The method to reconstruct the imageis the same as is currently used on modern MRI scanners. As long as thepermanent magnet field is precisely known, there would not be a need toshim the magnet.

Another example option is to use a plurality of very coil elements (suchthat there size approaches the desired resolution) such that theirimaging area can be used to determine spatial encoding in the θ and zdirections while continuing to extrapolate from the non-uniform B₀ fieldfor the r gradient. Three example implementations of this design areshown in FIG. 48A-C. FIG. 48A depicts an array of loop coils where theloops coils can be placed in a horizontal and a vertical configuration.FIG. 48B depicts a butterfly coil wrapping the perimeter, and finallyFIG. 48C shows an array of striplines. These all serve to create a B₁field orthogonal to the magnet generated B₀ field, and to receive an MRsignal in the same orientation. Many combinations of these elementsexist to enable a full volume imaging area surrounding the coil with afocused end-fire imaging area. In FIG. 48C, the stripline coils are usedin combination with the magnet of FIG. 47A, and the gradients of FIG.47B.

Another example embodiment may employ a plurality of very small coilelements and physically move the coil in the θ and z directions, and usethe change in signal over time to serve as the gradients for thesedirections.

In a further embodiment, no physical gradients are used. Instead, themotion of a transmit/receive coil is used to artificially generate thesituation of a magnetic field varying in space. By arranging a set oftransmit/receive coils around a probe, the motion required tosuccessfully approximate physical gradients would be rotating motion, aswell as motion in the ‘z’ direction, along the axis of the probe. Signalacquisition would take place at the same time as the probe motion. Thisembodiment uses the same magnet configuration as FIG. 47A.

This spatial information can be captured with a navigation system andrelayed to the MR system. Again, the non-uniform B₀ field is used forthe r gradient. The physical movement of the coil can be achieved bymoving the arm that is otherwise used to rigidly hold the coil in place.Consistent movement of the arm can be realized through automation of thearm to achieve consistent and constant movement along specificdirections. Alternatively, the movement of the coil may be achieved byretracting the coil into the handle in a consistent manner while thehandle is held rigidly in place by an external mechanical arm.

As noted above, in another example implementation, the magnet may be aspherically shaped magnet. The following three example implementationsmay be employed in such as case. The first embodiment employs gradientcoils to generate spatial encoding in the θ and φ directions, andextrapolates from the non-uniform B₀ for the r gradient, as shown inFIG. 49.

It is noted that each gradient will require a separate gradientamplifier. The outside of permanent magnet is typically coated in anon-conductive coating. Therefore, the gradient wiring may be wounddirectly against the permanent magnet itself. Alternately, a spacercould be placed between the permanent magnet and the gradient coils. Thegradient coils are used to generate spatially varying magnetic fields indirections orthogonal to the static magnetic field. In this case, oneset of gradient coils generates a field in phi (angle, around theprobe), and the other generates a field in theta (other angle around themagnet). The final gradient, r, radially away from the permanent magnet,is achieved through the natural drop-off in magnetic field strength of apermanent magnet. It should be noted that the gradients do not need tobe perfectly linear, as long as they are known. Provided the spatialpatterns of the gradient coils are well plotted, a modern reconstructionengine can undo any warping that occurs.

Another example implementation involves the use of a plurality of verysmall coil elements such that their imaging area can be used todetermine spatial encoding in the θ and φ directions while continuing toextrapolate from the non-uniform B₀ field for the r gradient.

In another embodiment, a plurality of very small coil elements may beused in conjunction with physically moving the coil in the θ and φdirections, and use the change in signal over time to serve as thegradients for these directions. Once again, the non-uniform B₀ field isused for the r gradient.

The coil array surrounding the magnet may be selected from the elementsdescribed within to generate and receive orthogonal B₁ fields. Thedesigns may be used either with or without externally applied gradientsas noted. In the latter scenario, the combination of the magnetic fieldpattern, B₀, and the sensitivity profile of each element in the arraymay be used be to decode the spatial information in combination with thecoil's physical position in space. As such, the port coil's movementsmay be tracked to provide z, and θ (or θ and φ for a spherical system)data and the radial information can be extrapolated from the non-uniformB₀ field.

2.13 Housing Material/Cannula Having a Susceptibility Map

Magnetic susceptibility is a measure of how a material reacts to amagnetic field. It is given by the equation M=χH where M is themagnetization and H is magnetic field. Susceptibility (χ) is related tomagnetic permeability by the equation χ=μ_(r)−1. Although there is onlya small susceptibility difference between Air (0.36E-6) and Water(−9.05E-6), this is enough to distort MR images, particularly diffusionweighted imaging (DWI) and the related diffusion tensor imaging (DTI).This distortion is particularly seen at the front of the brain, wherethe air of the sinuses causes a susceptibility difference in this area.

Typically, susceptibility induced distortions are ignored in MR, as theydo not impact a radiologist's ability to read the scan. However, in anintraoperative setting, geometric accuracy can be of the utmostimportance. Indeed, if an insertable MR imaging device is inserted intoan access port, as described above, even if the insertable MR imagingdevice is formed from a non-magnetic material, the ability to performgeometrically accurate diffusion scans will be compromised if theinsertable MR imaging device does not have a close susceptibility matchto the brain.

Therefore, in some embodiments, insertable MR imaging devices areformed, at least in part, from a material having a susceptibility thatis similar to that of the tissues being imaged (e.g. the tissues thatreside adjacent to the insertable MR imaging device when it isinserted). A susceptibility that is similar to that of tissues is asusceptibility that differs from that of the tissue being imaged byapproximately (−9.05E-6) which is similar to the range for water.

Examples of materials with a close susceptibility map to water (softtissue in the body), which could be employed to fabricate an insertableMR imaging device, include nylon, silicon nitride, Teflon®, polysulfone,magnesia, steatitie, carbon fiber composites, Vespel® (acetal),zirconia, plexiglass, PEEK, wood and copper. In the class of carbonfiber composites, one other material is pyrolytic graphite foam (PGFoam, described in ‘Pyrolytic Graphite Foam: A Passive MagneticSusceptibility Matching Material’ by Lee et al, Journal of MagneticResonance Imaging 32:684-691 (2010)). Suitable materials for forming theshell of an insertable MR probe include polycarbonate, Teflon, and PEEK,and a suitable material for forming the dielectric portion within thebody of an insertable MR probe is Teflon.

In one embodiment in which an access port is employed with one or moreinsertable MR imaging devices, such as an insertable MR imaging probe oran insertable imaging sleeve, the access port and the insertable MRimaging devices are formed, at least in part, from a common materialthat is susceptibility matched to the tissue being imaged.

Furthermore, as described in Section 1.1, the access port and aninsertable MR imaging probe may be configured such that a close fit isachieved between the outer wall of the insertable imaging probe and theaccess port, thereby reducing the amount of air between the imagingprobe and the access port. This avoids MR image distortion caused bydifferences in susceptibility between air, tissue, and the materialsforming the access port and the insertable imaging probe.

It is noted that while large conductor sizes can cause eddy currentproblems in scanners, the size of the port in the embodiments consideredherein is expected to be sufficiently small to avoid eddy currentproblems.

3. Ultrasound

The present section describes various embodiments employing one or moreultrasound (acoustic) transducers (ultrasound elements) for imagingwithin an access port, in order to achieve ultrasonic imaging within aninternal area of interest.

As described above, some embodiments described in the present sectionmay complement a minimally-invasive neurological procedures (such assurgical procedures) whereby a procedure involving internal brain tissueis conducted via a narrow corridor formed via an access port. Forexample, an insertable ultrasonic imaging device may be adapted to bereceived (e.g. slidable received, as described in Section 1 above) intothe bore of an access port and exploit its close position to produceultrasound images, such as ultrasound images of the surrounding(lateral) brain tissue and/or forward-looking (anterior, distal)tissues. Such images may be used during medical procedures (e.g.surgical procedures), potentially providing detail that would otherwisenot be obtainable with current technologies (or would otherwise beobtainable with less resolution or signal to noise, using currentlyavailable technologies).

The ultrasound transducers may be provided within an insertable imagingdevice according to a number of different configurations. For example,in one example implementation, a single ultrasonic transducer may beemployed (including a single ultrasonic transducer with multipleelectrical connections to act as a phased array). In another exampleembodiment, an array of ultrasonic transducers may be provided within aninsertable imaging device, such as a radial array spanning a radialsegment of the insertable ultrasonic imaging device, or as an array oftransducers with an opening at the center to enable access to distaltissue through an internal bore.

The ultrasonic elements of an ultrasound array may be realized usingknown technologies such as piezoelectric transducers. It will beunderstood, however, that other solid-state transducers may alternativereplace the piezoelectric transducers.

In some embodiments, an array of ultrasound transducers may be arrangedas a phased array to generate beams that may be swept in predeterminedfashion. This can be realized using a transducer driver circuit thatimplements necessary signal processing capability.

An array of ultrasonic transducers may be arranged sparsely so that thetissue region beyond the distal end of the insertable ultrasonic imagingdevice may be clearly visible for visual inspection or for simultaneousimaging through the use of an additional imaging device, such as anexternal videoscope. The array of transducers may be sparsely arrangedwithout compromising the ability to acquire a complete ultrasonic volumeimage by appropriately overlapping the fields of adjacent transducers.Transducer configurations may be realized, for example as described in“Design Optimization for a 2D Sparse Transducer Array for 3D UltrasoundImaging”, Proc IEEE Ultrasound Symposium, 2010 Oct. 11; 2010:1928-1931.

Insertable ultrasonic imaging devices according to the embodimentsdescribed here may be, for example, an insertable ultrasonic imagingprobe, an insertable ultrasonic imaging introducer for inserting anaccess port, an access port with one or more integrated ultrasonictransducers, one or more ultrasonic imaging sleeves that are configuredto be coaxially inserted into an access port, or various combinations ofthese insertable imaging devices, as illustrated in Section 1. Variousexample implementations of such insertable ultrasonic imaging devices,and various ultrasonic transducer configurations, are described indetail below.

The ultrasonic transducer configurations presented below are provided asexample and non-limiting implementations of potential configurations.Some of the following embodiments provide configurations that produce aforward-looking focused receiving or transmitting zone. In other words,some of the following embodiments provide transducer configurations thatare sensitive to regions anterior to the longitudinal probe body(regions beyond the distal end of the probe body), e.g. in an end-firedconfiguration beyond the distal region of the body of the imaging probe.Such embodiments may be included or incorporated within the variousimaging probes described within this disclosure.

3.1.1 Insertable Ultrasonic Imaging Probes

FIGS. 50A-C illustrate three example implementations of an insertableultrasonic imaging probe having one or more distal ultrasonictransducers for imaging tissues in a forward-looking direction within anaccess port. FIG. 50A shows an embodiment with a single circulartransducer 5010. This configuration supports the insertion of a secondimaging probe through the central opening 5015. FIG. 50B shows anembodiment having a circularly-arranged ultrasonic array with MRtransducer elements located in the opening. FIG. 50C shows an embodimenthaving a radial array of transducer elements, with an opening in themiddle. The opening in the middle allows access for surgical tools, orlight for multi-modality imaging. The imaging device may be a localultrasound receiver and transmitter, or a local ultrasound receiver usedin conjunction with an external ultrasound transmitter, or an internalultrasound transmitter used in conjunction with an external ultrasoundreceiver.

In an example embodiment as described herein, an ultrasonic transducerarray can be oriented around the peripheral of the port in an annularorientation for ultrasound imaging of the area surrounding the port.FIG. 64 depicts such an ultrasound imaging assembly. In the figure, anultrasound transducer array 6428 is oriented around a port 6429. Itshould be noted that the array 6428 can be of various types, includingbut not limited to, a flat phased array, a curved array, a phased sectorarray, a linear array, a multi-row array, and other 1D and 2D arrays.The ultrasound imaging assembly also consists of a backing layer 6420 todampen and consequently shorten pulse duration. In addition anelectrical connection layer 6422 creates a communication pathway betweenthe array and an ultrasound control system (not shown).

Wiring from the electrical connection layer provides the electricalconnection to the ultrasound control system not located in or on theport. Non limiting examples of this wiring may pass through the walls ofthe port through a conduit, or can be oriented on the inner or outersides of the port, as well as be used in conjunction with a PCB orflexible PCB, etc. It should be noted that the wiring refers to anymechanism to transfer the electrical signals or information they carrygenerated by the ultrasound signals from the array to the ultrasoundcontrol system where it may be collected and analyzed.

FIG. 51 illustrates an example implementation of an insertableultrasonic imaging probe having an ultrasonic transducer integratedtherein. In FIG. 51 a single ultrasonic transducer 5108 may beintegrated within the probe body and a 3D ultrasonic image-basedvisualization of the tissues surrounding an access port, into which theinsertable ultrasonic imaging probe is inserted, can be realized bymechanically (manually or robotically) rotating the insertableultrasonic imaging probe during its insertion and/or withdrawal, andreconstructing the volume image through the use of standard softwarereconstruction methodologies. In FIG. 51, introducer 5104 and port 5102when combined can produce insert imaging arrays in differentconfigurations, including arrays that are swept along distal and sidesof the port. Port insert with surface imaging array are shown as threepieces as elements 5106, 5108 and 5110 respectively. The radialarrangement of transducer arrays along the atraumatic tip of the imagingprobe 5104 enable the acquisition of ultrasonic image of the distal endof the port during insertion of the port towards a tumor 5112. Thetransducer arrays (such as the one illustrated in 5106) can be used astransmitters and receivers by allocating some transducers astransmitters and others as receivers. This is known as spatialmultiplexing of the transducer elements. In another embodiment, thetransducers may be multiplexed in time as transmitters and receivers. Inall of the configurations, the transducers may be energized usingstandard ultrasonic driver circuit such as that described in U.S. Pat.No. 5,590,658.

FIGS. 52A-F illustrate example implementations of an insertableultrasonic imaging introducer having of a single radial array ofultrasound transducers positioned such that optical view through theintroducer tip is not occluded. The top row shows introducer 5202 withan opening to the distal tip 5204 of the insert in a side view in FIG.52A and a perspective view in FIG. 52B. In FIG. 52C introducer 5202 isshown with a multimodality line scan array 5206. The multimodality linescan array 5206 may be composed of a combination of ultrasound elementand fiber bundles placed adjacent to each other. While the ultrasoundarray may be used for ultrasonic imaging, the fiber bundle may be usedfor spectroscopic analysis such as Raman Spectroscopy or the fiberbundle may be used to deliver pulsed laser to the tissue layer and thegenerated photo-acoustic waves are measured by the ultrasoundtransducer. The bottom row of this figure (FIGS. 52D, 52E and 52F) showsa similar embodiment, without the angulated imaging array at the bottom.

The example embodiment shown in FIG. 51A-C may be further refined toprovide an embodiment reducing the space within an access port, whileproviding sufficient space for including transducer arrays at the tip ofthe introducer. An example implementation of such an embodiment is shownin FIGS. 53A-C As shown in these figures, the insertable ultrasonicintroducer 5315 includes an array of ultrasonic transducers, optionallyorientated an oblique angle 5320 directed towards the tissue, providingan opening 5310 through which light may be delivered, or access forintervention. In this manner the device can be employed for imaging asit is inserted, or imaging can be performed while the port is moved todifferent areas within the body (e.g. the brain). In the exampleembodiment shown, the centre (5210) is open, while the sides, housingthe ultrasonic array, are employed for imaging. In this manner, theinsertable ultrasonic introducer can be inserted into the subject withtransducer elements covering the field with an angled side viewingarray, and optionally with forward-looking imaging provided by anadditional insertable ultrasonic imaging probe that is insertable intothe central bore of the introducer. The opening may be used to insert aprobe with another imaging modality, such as MR strip coils (FIG. 53C).Hence, two imaging modalities may be combined in the same cavity and oneimaging modality may be optionally removed to make space for surgicalresection or tissue access.

In another example implementation, shown in FIG. 54A-C, the insertableultrasonic introducer 5402 may include a non-conical tip 5404 as seen inFIG. 54C, where the tip 5404 is offset to one side of the axis of theintroducer 5402. In this way, the innermost face of the tip 5404 canhave an array of transducer elements 5406 that can be aimed towards thetissue that is accessible by the aperture, and the outermost elementscan image the outside surface. In this way, the tissue can be imagedduring tissue resection. This introducer could be positioned deeper intothe surgical cavity as a means for the surgeon to explore the innerimaging volume concurrently with surgical resection.

3.1.2 Access Ports and Imaging Sleeves with Integrated UltrasonicTransducers

The preceding embodiments of Section 3 have disclosed various exampleinsertable ultrasonic imaging probes and introducers. However, it willbe understood that in alternative embodiments, one or more ultrasoundtransducers may be provided formed on or within (e.g. embedded orrecessed within) an access port, or a sleeve that is insertable into anaccess port, as initially described in Sections 1.3 and 1.4.

In one embodiment, one or more ultrasonic transducers are formed on, orembedded within, an access port, thus providing a hollow imaging sleevewherein instruments such as surgical tools can be inserted during amedical procedure. This provides an entry point for other imagingdevices, image guided therapies, or contrast agent administration. Thismay include biopsy tools, deep brain stimulation devices, thermalimaging equipment, or ultrasound devices among others. Such embodimentsare similar to the access ports with integrated MR coils, as disclosedin Section 2.6.

In other embodiments, an imaging sleeve with one or more integratedultrasonic transducers may be provided, where the imaging sleeve isinsertable into an access port, thereby providing a reconfigurable andoptional means of port-based-imaging while still providing a centralbore that provides access (direct or indirect) to internal tissues. Thisembodiment was introduced in Section 1.4, and is similar to the MRimaging sleeve embodiments disclosed in Section 2.6.

In one embodiment, one or more ultrasonic transducers are formed on, orembedded within, a sleeve that is slidably received within an accessport, thus providing a hollow imaging sleeve wherein instruments such assurgical tools can be inserted during a medical procedure.

3.2 Embodiments with Combinations of Multiple Insertable UltrasonicImaging Devices

Finally, it will be understood that, as described in Section 1.5 (and inSections 1.5.1-1.5.5), additional embodiments may be provided bycombining two or more of the above insertable ultrasonic imagingdevices.

For example, in one example implementation, an insertable imagingapparatus may include one insertable imaging device that includes anaccess port having an array of integrated laterally directed ultrasonictransducer elements, and an insertable imaging probe having an array ofultrasonic transducer elements that are oriented for forward-looking(end-fire) imaging.

4. Conductive Sensors for Local Resistance Map

In another embodiment, an additional measurement modality can berealized through the inclusion, on an insertable imaging deviceconfigured to contact the tissue, of an array of electrical sensors forthe generation of a local resistance map. This is achieved by sensingthe conductivity between pairs of conductors where the tissue forms partof the electrical circuit. By sharing one of the conductors, a map maybe generated by measuring conductivity between a shared conductor and anarray of complementary conductors that are individually addressable. Theresulting measurements may be then used to construct a vector indicatingthe physical orientation of least resistance.

For example, as shown in FIG. 55 an array of electrical conductors(cathodes or anodes, 5510 and 5500) may be placed along thecircumference of an access port near its distal portion 5505 of the port5535, where each conductor 5510 is individually addressable. FIG. 55also shows the distal view of the port 5540 illustrating the arrangementof exposed contact points that form one polarity for measuringconductivity. A conductor of the opposite polarity may be presentedthrough a needle or a modified surgical tool 5515. Electrical contactwith exposed conductors 5510 is established via conductors 5500 embeddedin the sleeve of the port. One polarity of an external current source isattached to these conductors at the proximal end of the port which willbe outside of the tissue throughout the surgical procedure. Electricalconnection between the current source and the conductors 5500 may beestablished, for example, using welded connection, spring-loadedconnection or clamps. All these connection mechanism are commonly usedin medical and laboratory equipment. The opposite polarity of the samecurrent source is provided through a needle or modified surgical tool5515. A surgical tool may be modified for this purpose by constructing atool with non-conductive material and providing a conductive point onlyat the tip of the tool. Hence, electrical contact is established by thesurgical tool only at a specific point at its tip. Such specificconductive contact may be placed at any predetermined position on thesurgical tool.

The conductance or resistance measured from the needle tip 5515 to eachof the array elements 5510 at the distal end of the port can be used toconstruct a vector map that can be used to infer arrangement ofconductive tissue structures such as nerve bundles. Vector components5532 and Vector sum 5530 illustrates inferring nerve bundle direction5530 based on multiple vector component measurements 5532. The geometriclocation of each measurement electrode (5510) is known a priori sincethis is fixed by design. Further, if the electrode located on thesurgical tool (5515) is positioned at the centre of the port at thedistal end, then relative orientation of current paths from the surgicaltool's tip to each of the measurement electrodes (5510) is known. Sinceeach measurement electrode (5510) is individually addressable, thecorresponding conductance along that specific orientation can bemeasured. Hence, a vector can be used to represent the magnitude anddirection of each of the measured conductance. The resulting vectors canbe then added using standard vector addition methods to arrive at asingle vector that represents the magnitude and direction of conductancein the region of the tissue that is in contact with the distal end ofthe port. The orientation of conductance vector will imply the physicalorientation of conductive tissue (nerve bundles) that is in contact withthe distal end of the port. The measurement can involve DC current oroscillating current. For example, oscillations in the range of 20 kHz to100 MHz result in significant differences in dielectric properties ofthe tissue when the region under investigation is breast tissue(reference: “Dielectric properties of breast carcinoma and surroundingtissues”, IEEE Trans. BME, Volume 35).

Such measurement may be also extended to discerning bioelectricdifferences, so that presence of sufficient healthy tissue margin can beconfirmed after resecting tumor tissue. For example, bulk of tumortissue may be resected first and then above described tool may beintroduced in the open cavity left after resection to assess theelectrical characteristic of the tissue surface. The conductancemeasurement can be used to assess if the residual tissue left afterresecting bulk of the tumor still contains tumor tissue. This inferencetechnique is described in detail in “A Review of Parameters for theBioelectrical Characterization of Breast Tissue”, Jacques Jossinet,Mchel Schmitt, Annals of the New York Academy of Sciences, April 1999.

In another embodiment, a series of real-time sensing electrode arraysmay be located on the introducer, where the sensing arrays recordphysiologic information as the access port is introduced into thetissue, or is repositioned within the patient.

Example implementations of such an embodiment are shown in FIG. 56.FIGS. 56 (A) and (B) illustrate implementations where outside of theport is lined with sensor elements. Such sensor elements may be simpleelectrical contacts that are individually addressable (as described forFIG. 55). FIG. 56 (C) illustrates the arrangement of such sensors fromtop view of ports shown in (A) and (B). Such conformable sensors may beconstructed from flexible organic transistors and circuits as describedin “Flexible organic transistors and circuits with extreme bendingstability,” Sekitani et. al., Nature Materials, Vol. 9, December 2010.Another approach to embedding sensors on the walls of the introducer orthe port may be as described in “A Locally Amplified Strain Sensor Basedon a Piezoelectric Polymer and Organic Field-Effect Transistors,” HsuY-, Jia Z, Kymissis I., IEEE Transactions on Electron Devices. 2011; 58(3). Also, the port may be constructed with a flat transparent bottomwhere only radial portion (a sector, 5620) is occupied by sensingelectrodes. The sensing electrodes may be the same type as thosedescribed in FIG. 55. Further, FIGS. 56 (D) and (E) illustrate twodifferent perspectives of such a design. The sensors are preferablyarranged in a radial fashion (5620) so that the port can be rotatedabout its longitudinal axis to view and measure different portions ofthe tissue that is in contact with the flat bottom of the port. In otherwords, the rotating action exposes different regions and hence theentire bottom surface can be visually analyzed while the sensorsarranged radially can be used to make electrical measurements. A portwith a flat transparent bottom is typically introduced in the cavityafter an introducer is removed from the tissue area.

Another example implementation is shown in FIGS. 57 (A) and (B), wherethe access port is lined with multiple elements of an electrode array.These electrodes can be employed for a number of uses, including, butnot limited to, measuring physiologic activity, stimulating andmeasuring the response of nerves and tissues, and measuring strains (asa series of strain gauges). The electrode arrays may be also used tostimulate regions of the tissue in direct contact with the port. Hence,functional electrical stimulation may be performed using the same portduring neuro surgery. In other words, specific regions of the brain thatis in contact with the port may be stimulated while the same portprovides access for surgical resection.

The front tip of the introducer may be lined with piezoelectrictransducers to measure contact strain as the introducer is inserted inthe tissue. Alternate means of measuring contact strain may beimplemented on the introducer tip as described in “A Locally AmplifiedStrain Sensor Based on a Piezoelectric Polymer and Organic Field-EffectTransistors,” Hsu Y-, Jia Z, Kymissis I., IEEE Transactions on ElectronDevices. 2011; 58 (3). FIG. 57(C) illustrates the arrangement ofelectrodes from the top view of the same port illustrated in FIGS. 57(A) and (B). Finally, FIGS. 57 (D), (E) and (F) illustrate arrangementof strain gauges at the tip of the introducer. The strain gauges may bepiezoelectric transducers (5710) that are exposed on the surface andelectrically connected (5720) to the proximal end of the port. Theproximal end has electrical wires directly welded or attached viaspring-loaded contacts (not shown). The wires are then connected tostandard strain measurement system (not shown) such as a WheatstoneBridge (as described in “Instrumentation for engineering measurements”,Daily, James W. et. al., Engineering instruments, pg. 584, Wiley (NewYork)). The latter measurement system is a common means of measuringstrain signals using a current source.

5. Optical

Insertable optical imaging devices according to the embodimentsdescribed here may be, for example, an insertable optical imaging probe,an insertable optical imaging introducer for inserting an access port,an access port with one or more integrated optical devices or channelsprovided therein, one or more optical imaging sleeves that areconfigured to be coaxially inserted into an access port, or variouscombinations of these insertable imaging devices, as illustrated inSection 1. Various example implementations of such insertable opticalimaging devices are described in detail below.

5.1 Insertable Imaging Device with Integrated Optical Channels

The terms optical fiber and light guide can be used interchangeably inthe following section. The optical fibers or light guides provide lightdelivery and/or collection from the tissue, with each fiber beingpurposed for illumination, light collection, or both. In addition,imaging could be performed using an insert optical imaging devicecomprising of a coherent array of fiber optics or light guides. In theseconfiguration, each optical fiber or light guide provides a singleillumination and/or collection measurement, which when combined with allother fibers or light guides provides a plurality of spatialmeasurements or an image.

In some embodiments, optical measurements and imaging can be performedusing fiber optics or light guides integrated into the walls of theaccess port as seen in FIG. 58 or in an insertable sleeve as seen inFIG. 59, or as an insert device as seen in FIG. 60.

FIG. 58 illustrates an example of light guides in the walls of an accessport. At the distal end of an access port 5802, optical fibers or lightguides 5804 can be bare or fitted with optical elements 5806 includingmicrolenses and gradient index lenses to focus and/or collimate theillumination and collection light exiting and/or entering the fiber orlight guide. Micromirrors can also be utilized to redirect theillumination or collection light in the desired direction. In addition,optical diffusers can be utilized at the distal end of the fibers orlight guides provide directionally homogenized illumination light.Different configuration (i.e., lens, mirror or diffuser) of the distalend of fibers or light guides is illustrated in FIG. 61.

On the proximal end of the access port, sleeve, or insert device thefiber optics can be bundled together into a single or multiple fiberoptic bundle cables as seen in FIG. 60. The proximal end of light guidescan be optically and mechanically coupled to fiber optic cables, whichcan be similarly bundled together into a single or multiple fiber opticcables. A variety of optical imaging modalities can make use of thesefiber optic or light guide structures including, but not limited to thefollowing diffuse optical imaging (DOI), diffuse optical tomography(DOT), fluorescence diffuse optical tomography (FDOT) make use ofmultiple illumination and collection fibers to acquire opticalmeasurement where the illumination and light collectionlocations/geometries are varied.

The acquisitions of measurements with vary illumination and detectiongeometries is used to construction a volumetric image of opticalproperties of the tissue (absorption, scattering, fluorescence, etc.),typically in a tomographic fashion. The multiple illumination andcollection fibers or waveguides also form an ideal platform formultichannel or multiplexed optical coherence tomography (OCT). Theacquisition of an OCT A-scan can be done through each fiber or lightguide by either multiplexing using a single OCT detector, havingdetector for each fiber or light guide, or using spatially separatedpixels or rows on an array or 2D detector. The fibers or light guidescould also be used for excitation light for photoacoustic imaging (PA)if used in conjunction with an ultrasonic transducer to acquire thestimulated pressure wave, in this case the fibers or light guides wouldbe used to delivery excitation light. More conventional optical imagingcould also be performed using these fiber or light guide structures,particularly the insert coherent array where imaging is performed is asimilar manner to conventional fiberscopes.

Beyond optical imaging modalities, these fiber or wave guide structurescan be used for a wide variety of optical measurements eitherindividually or as part of a multichannel systems. These measurementsinclude, but are not limited to spectroscopy, NIR spectroscopy, Ramanspectroscopy, surface enhanced Raman spectroscopy, stimulated Ramanspectroscopy, and coherent anti-stokes Raman spectroscopy, fluorescencespectroscopy.

5.2 Insertable Optical Imaging Device with Integrated Optical ImagingCamera

In one example embodiment, a lower resolution video chip with anintegrated lens may be placed as an insert to acquire local videoinformation about the distal portion of the port.

According to various example implementations, the optical imaging devicemay employ imaging modalities such as visible imaging, infrared imaging(e.g. near infrared imaging), hyperspectral imaging, and Raman Imaging.

5.3 Imaging through a Conical Distal Portion of Introducer or AccessPort

In some embodiments, the design of the distal portion of the access port(6200 in FIG. 62 (A)) or the introducer (6210 in FIG. 62 (B)) can beconical in nature without compromising the visibility of the path aheadof the conical portion. This can be realized through use of Fresnel lensthat is conical in shape (FIG. 62 (C)). The refractive indices of theconcentric rings (6230) in the Fresnel lens can be modified such thatthe focal point of rays entering the various concentric rings iscoincident. However, the facets or the grooves between concentric ringscan generate visible artifacts and should be below the visual acuity ofthe human eye (approx. 1 arc minute). The pitch or width of theindividual lens components should be such that Moiré patterns areminimized for the observation distance. The Fresnel lens is composed ofconcentrically arranged prisms. The exact focal point is adjusted byappropriately choosing slope angles and draft angles of the Fresnel lensprisms. The slope angle faces correspond to faces of prism thatsummatively create the intended image and draft angle faces are used totransition from one Fresnel prism to the adjacent Fresnel prism. Thesemethods are described in optical design text books (reference: “OpticalDesign using Fresnel Lenses: Basic principles and some practicalexamples,” Arthur Davis et. al., Optik & Photonik, December 2007, No.4). The design is extended to a non-flat profile to match the conicalprofile of the port.

Any visible artifacts can be further reduced by acquiring the imagethrough the port using an external video scope and then correcting forartifacts caused by grooves located between concentric lens rings in theFresnel lens. A simple method for such correction is averaging of imagedpixels over an averaging area that is larger than the dimension of thedraft angle of the Fresnel lens prims. Another correction method wouldbe replacement of imaged regions corresponding to draft angle faces ofthe prism with values that are interpolated values of pixelscorresponding to image created by slope angle faces of the Fresnelprism. This can be achieved since the geometries of the concentricportions are known and the exact distance of the distal portion of theinsert port can be interfered from location of the port acquired throughnavigation systems or optical fiducial markers placed on the exposedsurface of the port. This design will enable the surgeon to observe thebrain structures as the port is introduced into brain. This embodimentis illustrated in FIG. 62. It should be noted that even though astandard staircase structure is illustrated for Fresnel lens, a uniformshape of Fresnel lens prisms will not provide the same focal point whenthe surface is not flat; instead, the slope angle and draft angle of theFresnel needs to be varied to accommodate the conical shape of theimaging surface. A standard methodology described in “Optical Designusing Fresnel Lenses: Basic principles and some practical examples,Arthur Davis et al., Optik & Photonik, December 2007, No. 4” can beemployed to arrive at the optimal angles for the prisms.

5.4 Embodiments Providing Delivery of Light to Distal End of Access Port

All port-based surgical methods are limited by the amount of light thatcan be delivered to the tissue at the distal end of the port duringsurgical procedure. Introduction of tools occludes light delivery fromexternally placed light sources such as overhead surgical lamps. Thislimitation can be overcome as follows. Light energy can be projectedonto the tissue via fibre bundles embedded in the walls of the port orby guiding the light through the port walls using total internalreflections within the wall. Light can be efficiently captured from anexternal light source using the ring located at the top of the port andthen guided within the walls. Appropriately shaped lens can befabricated along the top ring to maximize light capture and transmissionto the inside of the port walls. A symmetrical lens will not be asefficient as a radially asymmetric lens fabricated or mounted on the topring surface of the port.

In another embodiment, light energy could be delivered with minimalocclusion by utilizing walls of the port as light pipe. FIG. 63Aillustrates the design where the internal propagation of light beam 6305from the top of the port 6300 to the distal tip 6125 of the port isfacilitated by a slanted wall 6310. This can be further enhanced throughuse of a wall that has a gradually changing radius of curvature 6330) inFIG. 63B. FIGS. 63A and 63B are still limited by the amount of lightincident on the top surface of the access port. Additional light can becaptured and piped into the port through the use of lens structures 6340shown in FIG. 63C.

Although not shown in FIGS. 63A-C, the delivery of light from theproximal portion of the access port to the distal portion of the accessport can be facilitated by providing an outer layer on the outer portion(and optionally the inner portion) of the access port, where the outerlayer has a refractive index such that the refractive index contrastbetween the outer layer and the access port is sufficiently high tosupport total internal reflection of light introduced in the top of theport. The refractive index contrast may be selected so that theeffective numerical aperture of the access port is suitable for guidanceof the light incident on the top of the port, such that light introducedover a given angular bandwidth (or solid angle) is totally internallyreflected when light propagating within the walls of the access portencounters the outer layer.

This design aids in the collimation of light arriving at various anglesinto the port walls. This design can be further enhanced through the useof radially asymmetric lenses 6350 to maximize light capture, as shownin FIG. 63D. Finally, light emanating from the distal end into thetissue region can be preferentially directed using similar lensstructures fabricated at this tip 6360. Hence, particular f/# (alsoknown as 1 number′) of the output beam can be achieved based on thedesign of the lens at this tip.

6. Multiple Imaging Modalities

FIG. 53 illustrates one arrangement for combining multiple modalities.An outer coaxial array of ultrasonic transducers can be combined withone of open cavity, inner radial array of ultrasonic transducer orsmaller MR coil array. This arrangement allows the removal andintroduction of different imaging modalities during surgery.

In one embodiment, a smaller opening can be left in the middle of theprobe to facilitate access for surgical procedures. The insert probeshall be held at a consistent location using an external holdingassembly that shall be firmly and removably affixed to an externalreference frame used for the purpose of surgical navigation. Hence,local images acquired through the insert probe can be easily registeredwith pre-operative whole-head images. Alternatively, the insert imagingdevices may be secured to the skull surface.

In a further embodiment the insert-imaging array may consist of two ormore inserts that fit inside each other (see, for example, FIG. 10). Inthis way different combinations of imaging modalities can be used thatare complementary to one another for the appropriate surgical purpose.Shown on the top left of the FIG. 53A is an external port with anopening in the middle, that accommodates a pointed, atraumatic tipintroducer. On the bottom right of the FIG. 53C., we see the externalport on end view illustrated with an array of radially arrangedtransducer elements. Inside of this port can be placed multiple inserts.On the top right we see an additional ultrasound array, this array maybe an array with a different detection/excitation frequency, or a set ofelements that can be used in concert with the external array. In themiddle is shown a single element. This element may be an optical fiber,or a single ultrasound element. In the bottom is shown a radial array,where each arm of the array consists of multiple elements. In allexamples these elements may exchange ultrasound, optical or MRIelements. The opening 5310 in FIG. 53B may be used to excite tissueusing pulsed laser and the resulting photo-acoustic emissions may becaptured using the ultrasonic receiver array. In another embodiment, thepulsed laser may be targeted by a robotic arm positioned above the portwith the arm positioning the pulsed laser in a raster pattern or randomsampling pattern on the exposed tissue at the bottom of the port.

FIG. 57 illustrates an example embodiment involving both MR andultrasound transducer elements in the insert device placed in the port.The MR transducer coils may be constructed from strip lines, loops orbipolar coils. Further, the coils may or may not contain a local magnet.

In one embodiment the device provides localized magnetic resonanceimages that enables parallel imaging protocols by way of multiplechannel coil imaging, while also providing a means to enable additionalimaging modalities such as ultrasound, optical imaging, hyperspectralimaging and photo acoustic imaging. This device can be inserted and/orre-inserted during imaging protocols to provide updated MR images of thearea of interest during points of a surgical procedure. It should befurther noted that in the case of embodiments involving multiple imagingmodalities, the said modalities can be registered relative to each othersince the respective transducers are located at fixed geometriclocations relative to each other. Hence, image acquired in the firstmodality can be geometrically transformed to appropriately overlap withthe image acquired using the second modality.

The following are further examples where multiple transducers can beused with multiple imaging modalities:

6.1 MR-Elastography

Similarly, the stiffness of various regions of the brain that are closeto the port coil can be estimated using MR-elastography. This techniquepresents the elastrographic data as an image map. In this embodiment,the conductive elements along the perimeter of the port can beinterspersed with piezoelectric plates driven by a pulse generator thatoscillates at approximately 300 Hz. The resulting vibration istransmitted to the tissue and relative movement of the tissue can beimaged via MR imaging techniques. Hence, a stiffness distribution oftissues in the vicinity of the port can be generated to identifypresence of different tissue types. Use of this elastographicinformation to model tissue deformation is presented in PCT PatentApplication No. PCT/CA2014 050243, titled “SYSTEM AND METHOD FORDETECTING TISSUE, FIBER TRACT DEFORMATION” and filed on Mar. 14, 2014,the entire contents of which is incorporated herein by reference.

6.2 Other Imaging Modalities Involving Excitation of Tissue

In addition, proximity to the tissue, particularly in the case of thebrain, providing access through the skull and, hence, enables amultitude of tissue excitation methods previously not anticipated orpossible. For instance, one may provide a local audio vibrationalexcitation to allow for elastography imaging (using MRI, US or OCT), orprovide for novel photo-acoustic excitation strategies, including directexcitation down the port, or through the patients ear canals. In thecase of elastographic imaging, the stiffness of the tissue can bemeasured as the device is being driven through the tissue and thendisplayed to the surgeon. As described previously, use of opticaldelivery paths in the port enable the use of optical measurementssystems such as OCT for understanding elastographic property of localtissue and polarization imaging to visualize anisotropy of the tissue.

6.3 Insert Imaging Devices Including Mechanism of Infusing ContrastAgents

Additional designs embodiments of the distal portion of the insertcomponent include the ability to infuse into the adjacent surface, aknown concentration of contrast agent. In this way, a controlleddelivery of fluids can be delivered to targets of interest in ways notpreviously allowed due to the presence of the blood-brain barrier. Theinfusion strategy can include, for example, a pre-saturated surface ofcontrast agent; an irrigation tube or array of tubes on the surface,that can deliver saline, contrast agent, or chemotherapy locally thatallows for clearance of fluids (this allows for better distal surfaceimaging, as well as clearance of contrast agents to enable local bolusdelivery of agents); an integrated suction device or array to removefluids; or an activated array, that delivers agents only when activated(either by a touch probe, or interaction with the navigation system).

Such embodiments can be used to deliver a variety of contrast agents,such as MRI based contrast agents (gadolinium, iron-oxide particles,etc.), CT (Iodine), Ultrasound (micro-bubbles), photodynamic contrastagents (gold spheres, carbon nanotube agents), PET (nuclear agents).Including biological bound contrast agents.

In addition, the concept can be extended to include chemotherapy agents.In the manner described above, specific locations within the port fieldof view can be indicated (either through navigation system or touch),and the chemotherapeutic agents can be delivered to those areas. In thisway the systematic delivery of agents through the vascular system can beavoided. This provides the ability to deliver a high dose to an area ofinterest, as well as being able to delivery multiple agents to variousregions. Fast acting chemo-therapy agents may also be flushed from thearea.

To provide for even more accurate delivery of therapy, a combination ofdetection and treatment agent can be used, for instance photodynamictherapy. With the method described prior, localized delivery of agentscan be performed, and an external light source can be used to activatethe photo-sensitizing agent.

6.4 Bottom of Insert Component Having “Flat Transparent Surface Ladenwith Biochemical Assays”

In another embodiment, the distal portion of the insert component may bea flat transparent surface that is laden with biochemical markersarranged as a micro-array or as a binding surface with a single type ofbinding molecule. An embodiment of this may be a substrate (distalportion of port that is covered) that has specific receptors laid out inpatterns. A non-limiting example of a receptor may be calcitoninreceptor (reference: “The expression of calcitonin receptor detected inmalignant cells of the brain tumor glioblastoma multiforme andfunctional properties in the cell line A172,” Wookey et. al.,Histopathology, 2012 May, 60(6):895-910). The composition of thechemical assay shall be any of previously published biochemical means ofdifferentiating tumor and healthy tissues. The selective binding oftumor cells or particles associated with them may be measured using anexternal video scope equipped with sensors sensitive to the appropriatewavelengths (e.g. Hyperspectral imaging at specific wavelength ranges).Alternatively, the binding surface may be illuminated using a techniquesimilar to that described in US patent (U.S. Pat. No. 7,314,749) toautomatically identify selective binding of molecules and cells.

An example arrangement for illustrating this embodiment is shown in FIG.67. As seen in FIG. 67, specific receptors may be attached to agrid-like substrate 6702 at the distal end of access port 6706. Anexternally positioned camera 6704 may be used to detect selectivebinding of molecules to the specific receptors. Camera 6704 detectsthese binding through such chemicals as fluorophores attached to themolecules.

7. Tracking and Incorporation of Fiducial Elements 7.1 Tracking of Probe

Once the MR imaging probe has been inserted, it may be fixated to amechanical arm for stability during imaging, or to the port cuff orsurgical clamping device, or alternatively held in place manually. Thisport coil may form part of an overarching navigation system in whichcase the MR Imaging Probe's location will be tracked and recorded. Theuse of tracking system or vibration sensors located on the Imaging Probecan also enable detection of movement of the probe during measurementand appropriate compensation for motion artefacts introduced in theacquired data.

In addition, calibration elements may be included, as well as fiducials,to allow for accurate registration. Coupling this probe with a tracking,or position device will allow for 3D imaging reconstruction if theimaging planes of interests are known. Coupling this imaging device withexternal volumetric imaging systems (whole organ), will allow for alarger scale volumetric scan if needed (i.e. significant tissue removalor deflection during surgery).

Within the port coil, fiducial elements may be included for reference,navigation, or registration purposes. These fiducials may be T1 and/orT2 markers and are intentionally included within the imaging area of theMR probe. When the MR probe is used after the retraction of anintroducer, the former component may be equipped with a pressure sensorat the tip so that a signal is generated when the port coil reaches thetissue surface. This signal can be translated into a warning signal toalert the surgeon that the port coil has reached the tissue surface andhence prevent application of excessive pressure on the tissue surface.

8. Use of Insert Imaging for Minimally Invasive Procedures

FIG. 65 shows a flowchart depicting the stages of minimally invasiveport based surgical procedure where imaging is valuable as an integraltool. In FIG. 65, the first step is the incision of the scalp andcraniotomy (step 6502) where a bone flap is temporarily removed from theskull to access the brain. The next step is guidance of the access port(step 6504) into the brain typically with assistance of a navigationsystem. Thereafter, the surgeon will debulk the tumour or disease tissue(step 6506). The surgeon may follow that up with precision zone or fineresection (step 6508) to further remove any finer tissue details. Next,the surgeon could perform tissue margin treatment (step 6510) bydelivering therapeutic agents to the surgical site to remove anyremainning unhealthy tissue from the area and assure an optimalrecovery. The final step is closure verification (step 6512) whichinvolves the removal of the port and closure or suturing of the wound inaddition to the application of materials to assist in healing thesurgical area. Furthermore, in steps 6506, 6508 and 6512 bleedingmanagement is monitored and contained which is represented by 6514, 6516and 6518, respectively.

Several stages of a minimally invasive procedure, including similarprocedures applied to the brain, will benefit from the use ofappropriate imaging modalities. Application of specific imagingtechniques and their embodiments for surgical removal of brain tumors isexplained in the next several sections.

FIG. 68 shows a flowchart depicting the utilization of imaging data forcraniotomy/incision guidance, in particular, the different surgicalsteps and application of specific imaging modalities. The imagingmodalities can be broadly grouped into external imaging, internalscope-based imaging and port-based imaging to capture different scalesof clinically relevant images. All of these images may be co-registeredand presented to the surgeon using a unified framework (depicted as“Imaging Interface Layer” in FIG. 68).

The imaging devices used may consist of external imaging devices, eitherfull-volume or sub-volume surface arrays, port based insert-imagingdevices, external arm optical imaging devices, surgical tool basedimaging devices, or margin surface imaging devices. At each stage theappropriate contrast and resolution may be selected for imaging. Imagingusing various MRI sensors to cover various arrays of interest is shownin FIG. 26, where a full volume array is shown on the left 2602, aregional array in the center 2604, and a local port area coil on theright 2606. On the right image 2606, access ports (2608 and 2610)integrated with imaging coils is seen inserted into the brain.

FIG. 66 is an illustration demonstrating an example embodiment involvinginsert imaging devices with differing imaging fields and resolutions,shown as (A) and introducer imaging array, (B) a port imaging array, (C)a tool imaging array, (D) a surface imaging array. In FIG. 66, there arefour different scales and resolutions of imaging devices shown in thecontext of delivery of the devices to the tumor (top left 6602), imagingthe surgical field of the tumor, (top right 6604), imaging a thin volumealong the edge of the tumor (bottom left 6606), and imaging of a verythin volume of tissue, along the margin of healthy tissue (bottom right6608).

8.1 Use of Insert Imaging Modality to Obtain Improved Contrast ImagesRelative to Pre-Operative Contrast Images

In one embodiment, imaging contrast mechanisms that were acquired with apre-operative imaging modality, will be able to be performed with theinsert imaging modality, except with a higher performance (higher signalto noise, and/or higher resolution image). For instance, tissueanisotropy, water content, oxygen concentration, blood flow, tissuestiffness, etc.

8.2 Real-Time Imaging During Insert Process, Sulci-Based Port Delivery

In some embodiments, the device may be configured to perform variousmulti-modal imaging combinations in real-time while it is beinginserted. Imaging in this way allows for delivery of the insert deviceto the location of interest with updating imaging guidance. For example,the sulci may be detected as the device is inserted. These structuresprovide minimally invasive orifice access into the brain, and theirdistinctive folds and branch points can provide a means to navigate tothe point of interest. In addition, unique patterns of vessels can beused as internal landmarks. Most neurosurgical applications do not planthe delivery of the tracked devices along a specific trajectory, butrather a only target to a point—in the application of sulci-based portdelivery, the trajectory is also important so as to minimize the whitematter trauma of the patient.

Upon successful navigation, the body of the imaging device can then beremoved, while leaving the rigid tube structure in place to allow forsurgical access to the tissue. The outer sleeve can be inserted usingthe introducer through the sulci and subsequent retraction of theintroducer. The inner imaging array can be inserted at any time to allowfor re-imaging of the tissue.

8.3 Surgical Planning—Craniotomy/Incision Guidance

The first stage of surgery generally involves utilizing images of thewhole head, in order to determine the location of the diseased tissue,the minimally invasive access corridors, and the structures that need tobe avoided (vessels, white matter tracts).

Typically a pre-operative scan (done on a previous day) has been doneusing MRI or CT, that allows for diagnosis of the tissue, andvisualization of the critical structures in a single scan. If multiplescans are required (MRI and CT), they are registered using a variety ofstrategies. In some cases, intra-operative scanning (at the time ofsurgery) may be performed, before the incision is made into the head,which could provide for more accurate surgical guidance information asit is acquired at the time of the surgery. Current systems do notprovide for high performance imaging intra-operatively either due tolimited performance coils of MRI hardware.

Alternatively a localized coil may be used to image the region ofinterest that is important, for instance, the quadrant of the brain forwhich the incision is planned. Until the skull is opened in surgery, itis expected that the brain position would be substantially similar tothe position in which it was in for pre-operative imaging, however oncea piece of the skull is removed, the brain will swell outside of theskull, where it has been documented the shift of the brain at that pointcould exceed 1 cm.

Therefore quadrant, or whole head imaging done pre or post skullresection addresses the following concerns: differences in patientposition and general brain condition (brain sagging or swelling);pathologies causing shifts and displacements—i.e. growth of the tumor,fluid build up, internal bleeding since pre-operative imaging; brainshift due to skull opening-craniotomy (smaller with burr-hole; poortissue differentiation—higher resolution local imaging (higheracquisition matrix can be addressed when imaging a smaller volume ofinterest); the need to provide better visualization of tumor close tosurface for better surgical planning and compressed gyrus to locatesulcus for sulcus based approaches; and poor differentiation of sulci,nerves and tumor pre-operatively—focused local imaging will providebetter imaging locally (higher resolution, better contrast, betterdefined nerve fibers (more angular acquisitions, thinner slices).;reduced brain shift due to large craniotomy—better located craniotomyand smaller dura opening reduces brain shift; and more accurate locationof head supports (pinning) based on more accurate intraoperative plan(reduce head trauma associated with poor head pinning).

Imaging may be performed using a whole head coil array, a quadrantarray, or by positioning a port coil close to the entrance of the skull.In addition, according to embodiments disclosed herein, after the skullhas been resected, MRI imaging can be done using the insert coil, USimaging can be done through the burr-hole, or surface imaging can bedone through the dura using an external optical imaging system (photoacoustic imaging has been shown to image sulci through the skull anddura, where US will permit imaging through the dura, and can adequatelyvisualize sulci with a high frequency probe (upwards of 7 Mhz)).

MRI imaging can be directly registered to the pre-operative MRI images,or alternatively the structure of the gyrus, or blood vessels in thearea may be used to register to pre-operative structures. If thevisualization of the sulci is difficult to determine before thecraniotomy or dura opening, additional sequences may be acquired at thediscretion of the surgeon.

8.4 Guidance of Access Port

Once the pre-operative plan is updated, craniotomy is made, and openingmade in the dura, the challenge is delivery of the port to the tumor,following a minimally invasive path (as measured by white matter andcortex traversal), while following the selected path (often the sulci).The steps of the surgical procedure are shown in FIG. 69, incoordination with possible imaging modality utilization.

Imaging at a smaller field of view (less than 6 cm, 1 cm close totumor), a faster temporal resolution (approaching 30 fps), and higherresolution that is more appropriate to insertion of a port into thebrain (less than 1 mm to resolve sulci), will address the followingproblems at this stage of the procedure: travelling down an incorrectsulcus corridor; traversing or puncturing the sulcus; traversing orpuncturing critical banks of grey and white matter; puncturing/shearingor cutting a blood vessel; mis-targeting or displacing the tumor;avoiding moving off of pre-planned navigated pathway; navigating pastnerves in real-time (i.e. taking a non-linear pathway); measuring tissuestiffness to minimize tissue mechanical trauma; measuring tissuestate—measuring electrical activity and/or measuring tissue oxygenationand/or tissue pH, and/or tissue anisotropy.

It is expected that the introduction of the port, and introducer willdisplace a significant amount of tissue internally, as well as displacethe folds of the sulci as it is pushed into the brain. For tissues thatare stiffer than the surrounding brain tissue, for instance someclots/hematomas, cellular tumors, there will be an expected internalshift of tissue as the introducer pushes against the tissue.

In one embodiment, this displacement can be predicted with accuratesimulation, using a priori tissue stiffness information, geometricknowledge of the introducer and port, a biomechanical model of tissuedeformation, (using the skull as a boundary condition) and usingpre-operative imaging data. This model can be updated using real-timeimaging information as the introducer is positioned inside of the head,and more accurately if real-time imaging is performed using the in-situport. For instance, real-time ultrasound imaging done on the tip of theport, can detect tissue stiffness inside the brain. This information canbe used instead of the priori-predicted stiffness, and can provide abetter estimate of tissue movement. In addition, ultrasound can be usedto identify sulci patterns as the port is being introduced. These sulcipatterns can be matched to the pre-operative sulcus patterns, and adeformed pre-operative model can be generated based on this information.

Alternatively, the port can be guided based on the actual real-timeimaging from the port. In the most basic form is the use of an opticalpath to the bottom of the port by way of a set of glass fibers, or aclear path with a lens at the bottom that is aligned with an externalcamera (as described in a related patent application—see below).Alternatively a combination of an optical lens, and a plurality of USelements could be used. In this combination the US elements may bemechanically scanned, or focused appropriately to image forward andsideways, thus providing an optical and US image in real-time.Alternatively, or in addition, photo-acoustic imaging may be used withan external laser excitation, and receiving using the ultrasoundelements. Alternatively, or in addition, OCT may be used to measurelocal tissue structure, Doppler imaging, or in-combination withphoto-acoustic imaging. For the purpose of guiding the port intoposition, there should be at least a 1 cm forward field of view forimaging. Optimally the field of view would be larger when inserting intothe sulcus, and when approaching the tumor, it would be reduced, and theimaging resolution is increased.

It is expected there will be a discrepancy between the pre-operativeimaging data, and the real-time port information (US, OCT, photoacoustic, optical). This can be measured by matching sulci patterns,blood vessel positions, or by quantifiable common contrast mechanismssuch as elastic modulus, tissue anisotropy, blood-flow, etc. Thereal-time port information would be expected to represent the truth, andwhen there is a significant discrepancy, a scan would be done to updatethe volumetric MRI and/or CT scans to update the pre or intraoperativescanning volume. In the optimal configuration, an MRI port coil would beused in conjunction with an external MRI system to acquire a 3D volumedemonstrating sulci path, tumor, nerve fascicles by way of DTIacquisition, and blood vessels. As the acquisition time is typicallymuch longer than US, OCT or photo-acoustic imaging, it is not expectedto be used as a real-time modality, however it can be effectivelyutilized as a single modality to position the access port withpseudo-real time capability (typically not faster than 1 fps).

Alternatively sensors on the outside surface of the port, can measurequantifiable physical measures, such as electricalconductivity/resistivity, stress/strain, temperature in real-time. Thisprovides valuable physiologic information pertaining to the forcesapplied to the nerve fibers, the port (and associated tissues), and thenerve activations. This real-time physiologic information can be used toascertain tissue conditions around all surfaces of the port.

8.5 De-Bulking of Diseased Tissue and Precision Zone Resection

FIG. 70 shows a flowchart depicting the utilization of imaging data forde-bulking of diseased tissue. Once the port has been positioned intothe tissue of interest by way of imaging guidance, the introducer can beremoved and the access to the tissue granted through the opening in theport.

The objective at this point is to establish a pattern of tissueresection, bleeding management, and port alignment so as to remove themaximum amount of diseased tissue, while, minimizing trauma tosurrounding tissue. This will be done in conjunction with clearing themargins of the tumor, where the diseased tissue comes into contact withnormal brain tissue.

The process involves a multi-resolution approach to resection of tissueat a coarse resolution with coarse tools (for instance using scissors,forceps, tissue ablation, suction or large volume aspiration cuttingtool setting) in combination with real-time imaging, (external videoscope feed), and fine resection using shaving tools (for instance smallvolume aspiration cutting tool, or small focus laser ablation), incombination with high resolution imaging (high resolution focusedexternal video scope, tool based OCT, tool based spectroscopy, toolbased US, tool based photo acoustic). In each case, the imagingresolution, and field of view is appropriately sized to the surgicalimplement.

Imaging in this manner allows the following issues to be addressed:healthy to diseased tissue differentiation in vivo; visualization ofblood vessels to better manage bleeding and cauterization; imaging ofnerves in vivo to avoid their resection/damage; tracking of pathologysamples to known imaging properties (currently not possible in anysurgical or radiology system); and assessing the state of greymatter/white matter in-vivo.

Surgical resection through port necessitates focus on the local surgicalvolume of interest distal to the opening of the port and the volumebeyond. By tracking the port relative to the pre-operative, orpreviously acquired intra-operative images, the correspondingpre-operative volume can be presented relative to this opening. Theability to track a port in the context of the immobilized patient head,external scope and navigation system, is demonstrated in FIG. 8. FIG. 8is an illustration demonstrating an example simplified neurosurgicalconfiguration where a port 802 is held by a skull based guide clamp 804.Tracked tools 806 may be placed down port 802. Nearby is an equipmenttower 808 containing imaging and navigation system 820. Navigationsystem 820 assists in aligning port 802 using an automated imaging arm810, tracking camera 812 and external imaging scope 814. External videoimage and preoperative images are shown on two separate monitors 816 and818 respectively.

However as the surgery processes, this volume becomes a less accuraterepresentation of the actual tumor, margin and surround tissue position.In order to achieve a more accurate local representation, a new volumerepresenting the local region of interest can be acquired. For instance,an MRI port coil can be introduced into the coil and a 3D volume may beacquired (approximately 2 cm volume). In addition, a scan of the volumecan be accomplished using high-frequency ultrasound (5 mm-2 cm), OCT(2-3 mm), or photo-acoustic imaging (variable field of view withresolution, therefore 2 cm to 2 mm).

This newly acquired information can provide the best representation ofthe surrounding tissue for resection. When approaching the margins ofthe tumor, local imaging devices, or point source imaging can beutilized to define volumes on the order of 1 mm-5 mm. This is presentedin FIG. 72, which shows a flowchart depicting the utilization of imagingdata for precision zone resection. In this mode, the boarders of thediseased tissue can be resected, and the condition of the tissue can beestablished.

In addition, Raman spectroscopic probes can be used to gather chemicalinformation relating to the tissue, and the multiple imaging signaturesof resected tissue can be recorded and tracked relative to specificsurgical resection samples. This information will be important to selectthe appropriate margin treatment protocols, and help to identify tissuetypes relative to other tissues in the same patient, or betweenpatients.

One aspect of the present disclosure is the ability to use the distalsurface of the port, or any imaging devices inserted into the port toimmobilize tissue. This is demonstrated in FIG. 67, where on the bottomrow, a port insert is shown with an additional insert whose purpose isto immobilize the tissue at the end of the port. By doing so inconjunction with any of the insert imaging devices, very high-resolutionimaging, and accurate tissue location can be achieved in a mannercurrently not achieved (i.e. tissue immobilization relative to anexternal reference, controlling for tissue pulsation, respiration andgeneral movement). As will be discussed further, this providesunprecedented ability to perform tissue treatment and ablation.

8.6 Tissue Margin Treatment

Current surgical procedures are limited by the inability to image at avery fine resolution, provide fine tissue contrast, and provide tools toselectively resect small areas of tissue, or small populations of cells.The use of microscopes can be effective at the surface of the brain, butin deep tissue, or tissue with pulsatile flow, this is not possible. Inaddition, current tools, or the precision of the surgeons hand with ascalpel is limited to >400 micrometers. Relative to the novel imagingmodalities immerging, where resolutions of 10's of micrometers areachievable, this degree of surgical resection control is not sufficient.Even using traditional lasers at this scale is impractical with a zoneof damage >800 micrometers.

FIG. 73 shows a flowchart depicting the utilization of imaging data fortissue margin treatment. This concept is shown in FIG. 73 where theaddition of external therapy and internal therapy options are listed andincluded at the end of the procedure flow chart. In addition, this ispresented in FIG. 74, where an external imaging, and laser ablativedevice 7402 is shown positioned above a tracked port 7404. The innerport surface in this case is immobilizing the tissue relative to thelaser that is held in place by an external arm 7406.

In FIG. 74, the external camera 7402 is showing a view down the port7404 on the right with outlined regions 7414 defined by the surgeon inthe top right view 7408. In the middle view 7410 standard thresholdmethod may be applied to identify and segment area selected by thesurgeon. This region may be imaged using a second imaging modality. Inthe bottom view 7412 is the calculated treatment plan as formulated bythe treatment planning system, using the imaging, regions of interest,and surgeons input. In one embodiment the treatment planning system maycompute area of interest to estimate the mass of the affected tissue.The mass of the tissue and a priori knowledge of therapy absorptionproperties of the tissue may be used to compute the treatment dose sincedose is proportional to absorption rate of the therapy and mass of thetissue being treated. The therapy delivered may be selective tissueablation delivered by a pico-second laser as described in “Tissueablation with 100-fs and 200-ps laser pulses”, Nishimura et al.,Engineering in Medicine and Biology Society, 1998. Proceedings of the20th Annual International Conference of the IEEE (Volume:4). This methodavoids tissue charring and bubble formation. In another embodiment, thetherapy delivered may be in the form of pharmaceuticals delivereddirectly to the exposed tissue region. The latter approach bypassesblood-brain barrier since the tissue is directly accessed via a port.

It is well understood that the more of the tumor volume is resected, themore effective secondary treatment strategies can be, to provide morelocalized cellular level therapy. These therapies include radiationtherapy and chemotherapy. As with surgical approach, these therapiesalso follow the premise that the more healthy tissue is spared, thebetter the patient's recovery and longer-term functional outcomes. Afundamental limitation to this is the ability to do high resolutionimaging at the margins of the tumor, and high-resolution therapydelivery in conjunction. Combining the two and delivering therapyin-vivo through a port device, provides surface access and imaging, theexpected patient outcomes would be significantly improved.

Combining therapy and imaging in such a manner may be overcomesfundamental issues with plaguing therapy today: movement of tissuewithin body on the order of 2-5 mm from pulsatile flow, respirationlimits fundamental therapy delivery; skull and sensitive brain tissuemakes margins inaccessible; chemotherapies have been ineffective due toblood-brain barrier and non-selective killing mechanism; radiationtherapy has been ineffective due to cell killing mechanism, inaccuraciesof delivery, tissue differentiation, and collateral damage;high-frequency ultrasound cannot focus well through the brain; laserablation cannot limit collateral damage; photodynamic therapy inabilityto access tissue, and tissue delivery through the blood-brain barrier.

By providing localized access to tissues of interest, and de-bulking thediseased tissue to a small region and depth through a multi-resolutionimaging and resection approach, the problem of localized margintreatment can be more effectively managed in-vivo. In fact, the abilityto administer imaging contrast agents, externally activated therapyagents, locally targeted biological agents, and local chemotherapyagents are available. The ability to use surface imaging techniques,particularly with external imaging sources such as the automatedexternal imaging system, and specialized external laser ablative sourcesprovides a means to treat residual disease at a level finer than asurgeon's scalpel.

8.7 Closure Verification

As a final verification that the surgery has been successfullyperformed, the same smaller field of view, and higher resolution imagingapproach is performed in reverse as shown in FIG. 71. FIG. 71 shows aflowchart depicting the utilization of imaging data for surgical closureverification. Instead of focusing on smaller regions of interest as thesurgeon de-bulks the tumor and addresses the margins, the port iswithdrawn, and the surgeon images a larger and larger region of interestlooking for residual tumor, un-controlled bleeding, excessive seepage,surgical object left in cavity, and recovery of the tissue next to thesurgical cavity.

In some instances devices to assist in tissue recovery, such aschemotherapy delivery devices, or stem cell delivery devices may be leftin the cavity, or in the sulcus folds of the brain. In the case ofneuro-stimulation devices, the ability to image inside of the brain canenable predicting whether the anticipated surgical outcome will occur(for instance, Hall effect imaging with MRI, or local DTI to visualizenerve fiber integrity). Insert imaging may be done as the port iswithdrawn, and after the dura is closed. Additional imaging may be used,in conjunction with navigation tip tracing, and external opticalimaging, to define the appropriate geometry of bone flap and craniotomyclosure hardware. A final scan may be required to validate there is nointernal bleeding or excessive swelling after the surgeon has completed.

In some of the embodiments presented herein, an insert imaging device isprovided that allows for image acquisition using one or more multiplemodalities, and optionally the ability to acquire images at variousresolutions. Such a device may enable the acquisition of images usingone of the following possible configurations, (or combinations ofconfigurations) through the surgical port:

1. Imaging of the distal end of the surgical port using an externallyplaced imaging device such as an external video scope, stand-off Ramansensor or hyper-spectral imager.

2. Imaging of the walls and the distal end of the surgical port throughthe use of sensors or sensor arrays placed in an insert in the port.This data may be used to construct 3D volume at high resolution due toproximal placement of sensors to areas of interest.

3. Image or analyze specific points on the exposed tissue located at thedistal end of the port using touch sensors such as Raman probes,conductance measurement probes (or arrays), spectrometer-on-a-chiplocated at the tip of surgical tools or assay-based bio-chemicalsensors. Any of the touch probes can be also tracked by attaching thetouch probes, such as a Raman probe, to a holding assembly that alsoincludes fiducial markers. Such tracking of the touch probe enables theassociation of measured data with exact location in the brain where suchdata was collected.

The device may be used in conjunction with therapeutic approaches, wherethe improved access afforded by the access port provides for betterimaging, and better bi-manual access to the tissue and bettertherapeutic delivery. The therapeutic mechanism may be integrated intothe insert imaging array, or located externally as shown in FIG. 74.Apart from energy-based therapeutic mechanisms, pharmaceuticals may beapplied directly at the surgical region due to the availability ofdirect access.

Examples of surgical and therapeutic fields that may be impacted by thepresent disclosure include: imaging and navigation used in surgery;intraoperative tumor removal and critical structure detection; accessingbrain regions via the skull base, removal of deep seeded tumors and stemcell detection; placement of probes and devices for deep brainstimulation, shunts, implantable devices; vascular brain defect surgery,Intra-cerebral hemorrhage (ICH); surgical procedures to addressneurodegenerative disease (Parkinson's, Alzheimer's, Huntington's,Dystonia, Major Depression, OCD, Epilepsy, Brain Tumor); and access toinner brain regions via various access ports to the brain.

8.8 Robotic Positioning

It is to be noted that at each stage of the surgery where guidance ofdevices, instruments, lasers, or surgical tools are performed, the meansof delivery and guidance of said devices may be performed by a humanoperator, a human-assisted robotic delivery, or a closed loop roboticguidance/delivery of the instruments. The insert imaging array conceptcan be utilized to augment robotic, or semi-automatic delivery of toolsby way of improved dynamic imaging, and/or static imaging withimmobilization. Examples of robotic positioning systems and methods areprovided in PCT Patent Application No. PCT/CA2014/######, titled“SYSTEMS AND METHODS FOR INTELLIGENT POSITIONING OF DEVICES DURING AMEDICAL PROCEDURE” and filed on Mar. 14, 2014, the entire contents ofwhich is incorporated herein by reference.

8.9 Surgical Workflow (Methods)

The utility of the present disclosure may be employed at a multitude ofstages of surgical intervention. While pre-operative imaging is used toguide the decision on incision location, local imaging is used to guidethe port along the sulci. This may be realized through ultrasound, MR,or OCT imaging modalities. Such images help identify potential risk ofdeviating from the sulci and potentially severing nerve bundles. Thesurgical region of interest may be identified through any of the tissuedifferentiation modalities such as MR, OCT, ultrasound and Ramanspectroscopy. The diseased tissue is then de-bulked and any bleeding maybe managed by preventing the excess fluid from occluding the image.Impact of glare and excessive fluid in the image can be minimizedthrough selective filtering achieved through Hyper-spectral imaging, NIRimaging and OCT.

Subsequent to de-bulking of tumor mass, selective regions may beidentified through probe-based Raman spectroscopy or assay-basedchemiluminescence achieved through the use of appropriate chemicalprobes at the distal portion of the insert component in the port.Presence of healthy tissue margin after resection of tumor may beconfirmed through the use of bio-electric sensors located at the distalportion of the insert probe. Upon confirmation that all tumor regionshave been removed, the port may be closed and external video scope basedimaging may be used to check for bleeding immediately below the dermis.

In FIGS. 68 to 73, the steps of the surgical procedure, as well asiterative components, such as re-imaging when tumor or tissue isremoved, bleeding is needed to be surgically controlled, when surgicalmargins need to be interrogated, or the iterative process of moving theport to a new area for interrogation or tissue resection is performed.Shown on the right side of the flow chart are the instances whereexternal Imaging (either pre-operative, intra-operative), external scopeimaging, port imaging (either at surface or inserted into the brain), ortool based imaging may be used. The imaging modalities previouslypresented may be utilized in different combinations as appropriate forthe task at hand. The arrows represent where the imaging information isincluded into the procedure, and the “Imaging Interface Layer”identified with a vertical arrow, represents a software and hardwareconfiguration that integrates the imaging into a representation that canbe utilized by the surgeon to assist in the procedure steps representedon the left of the figures above. The image sets may be simplyrepresented as 2D or 3D representations on a single, or multiplescreens, or fused together spatially, or temporally. When imaging setsare registered, either by way of mutual information, such as gradientchanges in the data (image or frequency space), or by registration ofcommon quantifiable contrast mechanisms (i.e. stiffness (elasticmodulus), density, anisotropy, etc.), the data sets may besuper-imposed, or one data-set can be used to morph the other data setto the same spatial coordinate frame (i.e. shift in tissue, or tissuebeing removed), or same temporal frame (i.e. imaging taken at differenttime). The software system can calculate similarity metrics betweenregistered sets, and suggested to the user that additional imaging setsare required, as the prior sets (taken pre-surgically, or earlier in theprocedure), are no longer representative of the current state of thetissue during that stage of the procedure. This concept can be extendedto control robotic manipulators, such that if the system determines theimaging data to fall outside of a particular threshold for a similaritymetric, the system will not allow the robotic system to operateautonomously, or will required user interaction.

The specific embodiments described above have been shown by way ofexample, and it should be understood that these embodiments may besusceptible to various modifications and alternative forms. It should befurther understood that the claims are not intended to be limited to theparticular forms disclosed, but rather to cover all modifications,equivalents, and alternatives falling within the spirit and scope ofthis disclosure.

Therefore what is claimed is:
 1. A magnetic resonance imaging probecomprising: a longitudinal body; first and second magnetic resonancecoils supported by said longitudinal body; wherein said first coil isconfigured to measure fields having a first direction within a region ofinterest beyond a distal portion of said longitudinal body; wherein saidsecond coil is configured to measure fields having a second directionwithin a region of interest beyond a distal portion of said longitudinalbody, wherein said first direction and said second direction areapproximately orthogonal; and electrical circuits housed within saidlongitudinal body for tuning and matching said first and second coilsand preamplifying signals detected by said first and second coils. 2.The magnetic resonance imaging probe according to claim 1 furthercomprising; a third magnetic resonance coil supported by saidlongitudinal body; wherein said third coil is configured to measurefields having a third direction within the region of interest beyondsaid distal portion of said longitudinal body, wherein said thirddirection is approximately orthogonal to said first direction and saidsecond direction; and an electrical circuit housed within saidlongitudinal body for tuning and matching said first and second coilsand preamplifying signals detected by said first and second coils. 3.The magnetic resonance imaging probe according to claim 1 or 2 whereinsaid longitudinal body is a cylindrical body portion configured to beslidably and removably inserted within an inner lumen of an access port.4. A magnetic resonance imaging probe comprising: a longitudinal body;one or more magnetic resonance coil arrays supported by saidlongitudinal body, wherein at least one coil array is a planar striplinearray comprising: an array of parallel stripline conductors providednear a distal portion of said longitudinal body, wherein said array ofparallel stripline conductors lies in a plane that is approximatelyorthogonal to a longitudinal axis of said longitudinal body; eachstripline conductor having longitudinal conductive paths extending fromends thereof and contacting a coil loop at a location that is remotefrom said distal portion; and a tuning capacitor serially providedwithin each longitudinal conductive path; and a plurality of matchingand preamplification circuits housed within said longitudinal body,wherein each matching and preamplification circuits is operativelycoupled to a single stripline conductor.
 5. The magnetic resonanceimaging probe according to claim 4 further comprising: an additionalplanar stripline array, wherein said additional planar stripline arrayis provided in a longitudinally spaced relationship relative to saidplanar stripline array, and wherein said planar stripline array and saidadditional planar stripline array are configured to sense fields indirections that are approximately orthogonal.
 6. A magnetic resonanceimaging probe comprising: a longitudinal body; one or more magneticresonance coil arrays supported by said longitudinal body, wherein atleast one coil array is an axial stripline array comprising: an array ofparallel stripline conductors cylindrically arranged and extending in alongitudinal direction; each stripline conductor having radialconductive paths extending from ends thereof and contacting an innerground conductor; and a tuning capacitor serially provided within eachlongitudinal conductive path; and a plurality of matching andpreamplification circuits housed within said longitudinal body, whereineach matching and preamplification circuits is operatively coupled to asingle stripline conductor.
 7. A magnetic resonance imaging probecomprising: a longitudinal body portion comprising one or more magneticresonance imaging coils; a handle portion that is removably connectableto said longitudinal body portion, wherein an electrical connection isformed between said longitudinal body portion and said handle portionupon mechanical connection of said longitudinal body portion to saidhandle portion; at least one electrical circuit for tuning and matchingsaid coils and preamplifying signals detected by said coils, whereinsaid electrical circuit is divided among said longitudinal body portionand said handle portion, and wherein at least a preamplification portionof said electrical circuit is housed within said handle portion.
 8. Themagnetic resonance imaging probe according to claim 7 wherein saidhandle portion comprises a matching portion of said electrical circuit.9. The magnetic resonance imaging probe according to claim 7 or 8further comprising one or more additional longitudinal body portions,wherein each additional longitudinal body portion is optionallyconnectable to said handle portion, and wherein each additionallongitudinal body portion comprises magnetic resonance coils of a uniqueconfiguration.
 10. The magnetic resonance imaging probe according to anyone of claims 7 to 9 wherein said longitudinal body portion is acylindrical body portion configured to be slidably and removablyinserted within an inner lumen of an access port.
 11. A magneticresonance imaging probe comprising: a longitudinal body; one or moremagnetic resonance coils housed within said longitudinal body, whereinat least one coil is a folded stripline coil comprising: twolongitudinal stripline conductors having a ground plane conductorprovided therebetween; a folded conductor segment connecting said twolongitudinal stripline conductors near a distal portion of saidlongitudinal body; a pair of matching capacitors, each matchingcapacitor provided between one of said longitudinal stripline conductorsand said ground plane conductor; a tuning capacitor serially providedwithin one of said longitudinal stripline conductors; and a preamplifiercircuit housed within said longitudinal body, wherein said preamplifiercircuit is operatively coupled to said folded stripline coil.
 12. Themagnetic resonance imaging probe according to claim 11 furthercomprising: an additional folded stripline coil comprising: additionallongitudinal stripline conductors oriented having said ground planeconductor provided therebetween; and an additional folded conductorsegment connecting said two additional longitudinal stripline conductorsnear said distal portion of said longitudinal body; and a pair ofadditional matching capacitors, each additional matching capacitorprovided between one of said additional longitudinal striplineconductors and said ground plane conductor; and an additionalpreamplifier circuit housed within said longitudinal body, wherein saidadditional preamplifier circuit is operatively coupled to saidadditional folded stripline coil; wherein said two additionallongitudinal stripline conductors are oriented such that said foldedconductor segment and said additional folded conductor segment areapproximately orthogonal, thereby forming a folded stripline quadraturepair.
 13. The magnetic resonance imaging probe according to claim 12further comprising a coil loop provided near said distal portion of saidlongitudinal body, said coil loop having a coil axis that isapproximately parallel to a longitudinal axis of said longitudinal body.14. A magnetic resonance imaging probe for performing intraoperativeimaging during a minimally invasive medical procedure involving anaccess port, the probe comprising: a probe body comprising a cylindricalbody portion configured to be slidably and removably received within aninner lumen of the access port, said cylindrical body portion comprisingone or more magnetic resonance imaging coils; at least one electricalcircuit housed within said probe body for tuning and matching said coilsand preamplifying signals detected by said coils; and one or more airpassage features provided on or with said cylindrical body portion forfacilitating expulsion of air from the inner lumen of the access portduring insertion of said cylindrical body portion into the access port.15. The magnetic resonance imaging probe according to claim 14 wherein adiameter of said cylindrical body portion is selected such that saidcylindrical body portion frictionally engages with the inner wall of theaccess port during insertion.
 16. The magnetic resonance imaging probeaccording to claim 14 or 15 wherein said one or more air passagescomprise one or more grooves formed within an outer surface of saidcylindrical body portion.
 17. The magnetic resonance imaging probeaccording to any one of claims 14 to 16 wherein said cylindrical bodyportion is formed from a material having a magnetic susceptibilityapproximately equal to that of water.
 18. An access port for performingintraoperative imaging during a minimally invasive medical procedurewhile providing access to internal tissue, the access port comprising: ahollow cylindrical body configured to be inserted into a subject forproviding access to internal tissue; one or more imaging elementsintegrated with and supported by said hollow cylindrical body; one ormore externally accessible connectors positioned near a proximal regionof said hollow cylindrical body; and at least one connection channelintegrated with said hollow cylindrical body for supporting signaltransmission between said externally accessible connectors and saidimaging elements; wherein at least one of said imaging elements isconfigured for imaging a distal region of interest beyond a distal endof said hollow cylindrical body.
 19. The access port according to claim18 wherein said hollow cylindrical body is enclosed at its distal end bya distal window, and wherein said least a portion of one of said imagingelements is integrated with said distal window for imaging the distalregion of interest.
 20. The access port according to claim 18 or 19wherein said imaging elements are provided in the form of an imagingarray.
 21. The access port according to any one of claims 18 to 20wherein at least a portion of one of the imaging elements is positionedto perform lateral imaging through a side wall of the access port. 22.The access port according to any one of claims 18 to 21 wherein saidhollow cylindrical body further comprises a distal window, and whereinat least a portion of one of said imaging elements is integrated withsaid by a distal window for imaging in a distal region of interest. 23.The access port according to any one of claims 18 to 22 wherein saidimaging elements comprise magnetic resonance imaging coils.
 24. Theaccess port according to any one of claims 18 to 22 wherein said imagingelements comprise optical focusing elements.
 25. The access portaccording to any one of claims 18 to 22 wherein said imaging elementscomprise optical imaging elements.
 26. The access port according to anyone of claims 18 to 22 wherein said imaging elements comprise ultrasoundimaging elements.
 27. The access port according to any one of claims 18to 22 wherein said imaging elements may be employed to perform imagingaccording to an imaging modality selected from the group consisting ofoptical coherence tomography, hyper-spectral imaging, polarized lightimaging, Raman Imaging, fluorescence Imaging, electrophysiology,computerized tomography, spectral x-ray, photo-acoustic imaging,positron emission tomography, thermal imaging.
 28. An imaging sleeve forperforming intraoperative imaging during a minimally invasive medicalprocedure involving an access port, the imaging sleeve comprising: ahollow cylindrical body configured to be slidably and removably receivedwithin an inner lumen of the access port; one or more imaging elementsintegrated with and supported by said hollow cylindrical body, whereinsaid imaging elements are positioned for imaging through the accessport; one or more externally accessible connectors positioned near aproximal region of said hollow cylindrical body; and at least oneconnection channel integrated with said hollow cylindrical body forsupporting signal transmission between said externally accessibleconnectors and said imaging elements.
 29. The imaging sleeve accordingto claim 28 wherein said imaging elements are provided in the form of animaging array.
 30. The imaging sleeve according to claim 28 or 29wherein at least a portion of one of said imaging elements is positionedto perform lateral imaging through a side wall of the access port. 31.The imaging sleeve according to any one of claims 28 to 30 wherein saidhollow cylindrical body is enclosed at its distal end by a distalwindow, and wherein said least a portion of one of said imaging elementsis integrated with said distal window for imaging a distal region ofinterest.
 32. The imaging sleeve according to any one of claims 28 to 31wherein said imaging elements comprise magnetic resonance imaging coils.33. The imaging sleeve according to any one of claims 28 to 31 whereinsaid imaging elements comprise optical focusing elements.
 34. Theimaging sleeve according to any one of claims 28 to 31 wherein saidimaging elements comprise optical imaging elements.
 35. The imagingsleeve according to any one of claims 28 to 31 wherein said imagingelements comprise ultrasound imaging elements.
 36. The imaging sleeveaccording to any one of claims 28 to 31 wherein said imaging elementsmay be employed to perform imaging according to an imaging modalityselected from the group consisting of optical coherence tomography,hyper-spectral imaging, polarized light imaging, Raman Imaging,fluorescence Imaging, electrophysiology, computerized tomography,spectral x-ray, photo-acoustic imaging, positron emission tomography,thermal imaging.
 37. The imaging sleeve according to any one of claims28 to 36 further comprising a tracking marker.
 38. An imaging system forperforming intraoperative imaging during a minimally invasive medicalprocedure involving an access port, the imaging system comprising: twoor more imaging sleeves according to any one of claims claims 28 to 36.39. The imaging system according to claim 38 wherein said imagingelements associated with at least two of said imaging sleeves employdifferent imaging modalities.
 40. The imaging system according to claim38 or 39 wherein at least one of the imaging sleeves is configured to beslidably and removably received within another one of said imagingsleeves, such that at least two imaging sleeves may be nested within theaccess port at the same time during a medical procedure.
 41. An imagingsystem for performing intraoperative imaging during a minimally invasivemedical procedure involving an access port, the imaging systemcomprising: an imaging sleeve according to any one of claims 28 to 37;and an access port having an inner lumen, wherein the diameter of theinner lumen is configured for slidably and removably receiving saidimaging sleeve.
 42. The imaging system according to claim 41 whereinsaid access port comprises: an additional hollow cylindrical bodyconfigured to be inserted into a subject for providing access tointernal tissue; one or more additional imaging elements integrated withand supported by said additional hollow cylindrical body; one or moreexternally accessible additional connectors positioned near a proximalregion of said additional hollow cylindrical body; and at least oneadditional connection channel integrated with said additional hollowcylindrical body for supporting signal transmission between saidexternally accessible additional connectors and said additional imagingelements.